RSpec fails when run via 'rake' but works as expected when run alone or via bundle exec spec.

Gem list

abstract (1.0.0)
actionmailer (3.0.5)
actionpack (3.0.5)
activemodel (3.0.5)
activerecord (3.0.5)
activeresource (3.0.5)
activesupport (3.0.5)
annotate (2.4.0)
arel (2.0.9)
autotest-fsevent (0.2.5)
autotest-growl (0.2.9)
autotest-rails-pure (4.1.2)
awesome_print (0.3.2)
aws-s3 (0.6.2)
bcrypt-ruby (2.1.4)
builder (2.1.2)
bundler (1.0.10)
cancan (1.6.0)
capybara (0.4.1.2)
celerity (0.8.8)
chalofa_ruby-progressbar (0.0.9.1)
cheat (1.3.0)
childprocess (0.1.7)
colored (1.2)
compass (0.10.6)
configuration (1.2.0)
cucumber (0.10.0)
cucumber-rails (0.3.2)
culerity (0.2.15)
dalli (1.0.2)
database_cleaner (0.6.5)
devise (1.1.8)
devise_invitable (0.3.6)
diff-lcs (1.1.2)
erubis (2.6.6)
factory_girl (1.3.3)
factory_girl_rails (1.0.1)
fastercsv (1.5.4)
ffi (0.6.3)
formtastic (1.2.3)
fuubar (0.0.4)
fuubar-cucumber (0.0.9)
gherkin (2.3.4)
haml (3.0.25)
heroku (1.6.3)
heroku_san (1.1.0)
i18n (0.5.0)
jquery-rails (0.2.7)
json (1.4.6)
json_pure (1.5.1)
kgio (2.3.3)
launchy (0.4.0)
mail (2.2.15)
mime-types (1.16)
nokogiri (1.4.4)
paperclip (2.3.8)
pg (0.10.1)
pickle (0.4.6)
polyglot (0.3.1)
rack (1.2.2)
rack-mount (0.6.13)
rack-test (0.5.7)
rails (3.0.5)
rails_best_practices (0.7.1)
railties (3.0.5)
rake (0.8.7)
redis (2.1.1)
redis-namespace (0.10.0)
resque (1.13.0)
rest-client (1.6.1)
rspec (2.5.0)
rspec-core (2.5.1)
rspec-expectations (2.5.0)
rspec-instafail (0.1.7)
rspec-mocks (2.5.0)
rspec-rails (2.5.0)
ruby-progressbar (0.0.9)
ruby_parser (2.0.6)
rubyzip (0.9.4)
selenium-webdriver (0.1.3)
sexp_processor (3.0.5)
sinatra (1.2.0)
sqlite3 (1.3.3)
sqlite3-ruby (1.3.3)
sys-uname (0.8.5)
SystemTimer (1.2.2)
term-ansicolor (1.0.5)
thor (0.14.6)
tilt (1.2.2)
treetop (1.4.9)
tzinfo (0.3.25)
unicorn (3.5.0)
vegas (0.1.8)
warden (1.0.3)
watchr (0.7)
wirble (0.1.3)
xml-simple (1.0.14)
xpath (0.1.3)
ZenTest (4.5.0)

Gemfile.lock.rb

GIT
  remote: git://github.com/just3ws/sitemap_generator.git
  revision: cb5d8d09c65d84469f828997b2c183311c40ff98
  branch: heroku
  specs:
    sitemap_generator (1.3.8)

GEM
  remote: http://rubygems.org/
  specs:
    SystemTimer (1.2.2)
    ZenTest (4.5.0)
    abstract (1.0.0)
    actionmailer (3.0.5)
      actionpack (= 3.0.5)
      mail (~> 2.2.15)
    actionpack (3.0.5)
      activemodel (= 3.0.5)
      activesupport (= 3.0.5)
      builder (~> 2.1.2)
      erubis (~> 2.6.6)
      i18n (~> 0.4)
      rack (~> 1.2.1)
      rack-mount (~> 0.6.13)
      rack-test (~> 0.5.7)
      tzinfo (~> 0.3.23)
    activemodel (3.0.5)
      activesupport (= 3.0.5)
      builder (~> 2.1.2)
      i18n (~> 0.4)
    activerecord (3.0.5)
      activemodel (= 3.0.5)
      activesupport (= 3.0.5)
      arel (~> 2.0.2)
      tzinfo (~> 0.3.23)
    activeresource (3.0.5)
      activemodel (= 3.0.5)
      activesupport (= 3.0.5)
    activesupport (3.0.5)
    annotate (2.4.0)
    arel (2.0.9)
    autotest-fsevent (0.2.5)
      sys-uname
    autotest-growl (0.2.9)
    autotest-rails-pure (4.1.2)
    awesome_print (0.3.2)
    aws-s3 (0.6.2)
      builder
      mime-types
      xml-simple
    bcrypt-ruby (2.1.4)
    builder (2.1.2)
    cancan (1.6.0)
    capybara (0.4.1.2)
      celerity (>= 0.7.9)
      culerity (>= 0.2.4)
      mime-types (>= 1.16)
      nokogiri (>= 1.3.3)
      rack (>= 1.0.0)
      rack-test (>= 0.5.4)
      selenium-webdriver (>= 0.0.27)
      xpath (~> 0.1.3)
    celerity (0.8.8)
    chalofa_ruby-progressbar (0.0.9.1)
    childprocess (0.1.7)
      ffi (~> 0.6.3)
    colored (1.2)
    compass (0.10.6)
      haml (>= 3.0.4)
    configuration (1.2.0)
    cucumber (0.10.0)
      builder (>= 2.1.2)
      diff-lcs (~> 1.1.2)
      gherkin (~> 2.3.2)
      json (~> 1.4.6)
      term-ansicolor (~> 1.0.5)
    cucumber-rails (0.3.2)
      cucumber (>= 0.8.0)
    culerity (0.2.15)
    dalli (1.0.2)
    database_cleaner (0.6.5)
    devise (1.1.8)
      bcrypt-ruby (~> 2.1.2)
      warden (~> 1.0.2)
    devise_invitable (0.3.6)
      devise (~> 1.1.0)
    diff-lcs (1.1.2)
    erubis (2.6.6)
      abstract (>= 1.0.0)
    factory_girl (1.3.3)
    factory_girl_rails (1.0.1)
      factory_girl (~> 1.3)
      railties (>= 3.0.0)
    fastercsv (1.5.4)
    ffi (0.6.3)
      rake (>= 0.8.7)
    formtastic (1.2.3)
      actionpack (>= 2.3.7)
      activesupport (>= 2.3.7)
      i18n (~> 0.4)
    fuubar (0.0.4)
      chalofa_ruby-progressbar (~> 0.0.9)
      rspec (~> 2.0)
      rspec-instafail (~> 0.1.4)
    fuubar-cucumber (0.0.9)
      cucumber
      ruby-progressbar (~> 0.0.9)
    gherkin (2.3.4)
      json (~> 1.4.6)
    haml (3.0.25)
    heroku (1.6.3)
      json (>= 1.1.0)
      launchy (>= 0.3.2)
      rest-client (< 2.0.0, >= 1.2.0)
    heroku_san (1.1.0)
      heroku
      rails (>= 2)
    i18n (0.5.0)
    jquery-rails (0.2.7)
      rails (~> 3.0)
      thor (~> 0.14.4)
    json (1.4.6)
    json_pure (1.5.1)
    kgio (2.3.3)
    launchy (0.4.0)
      configuration (>= 0.0.5)
      rake (>= 0.8.1)
    mail (2.2.15)
      activesupport (>= 2.3.6)
      i18n (>= 0.4.0)
      mime-types (~> 1.16)
      treetop (~> 1.4.8)
    mime-types (1.16)
    nokogiri (1.4.4)
    paperclip (2.3.8)
      activerecord
      activesupport
    pg (0.10.1)
    pickle (0.4.6)
      cucumber (>= 0.8)
      rake
    polyglot (0.3.1)
    rack (1.2.2)
    rack-mount (0.6.13)
      rack (>= 1.0.0)
    rack-test (0.5.7)
      rack (>= 1.0)
    rails (3.0.5)
      actionmailer (= 3.0.5)
      actionpack (= 3.0.5)
      activerecord (= 3.0.5)
      activeresource (= 3.0.5)
      activesupport (= 3.0.5)
      bundler (~> 1.0)
      railties (= 3.0.5)
    rails_best_practices (0.7.1)
      activesupport
      colored (~> 1.2)
      erubis (~> 2.6.6)
      haml (~> 3.0.18)
      i18n
      ruby-progressbar (~> 0.0.9)
      ruby_parser (~> 2.0.4)
    railties (3.0.5)
      actionpack (= 3.0.5)
      activesupport (= 3.0.5)
      rake (>= 0.8.7)
      thor (~> 0.14.4)
    rake (0.8.7)
    redis (2.1.1)
    redis-namespace (0.10.0)
      redis (< 3.0.0)
    resque (1.13.0)
      json (~> 1.4.6)
      redis-namespace (>= 0.10.0)
      sinatra (>= 0.9.2)
      vegas (~> 0.1.2)
    rest-client (1.6.1)
      mime-types (>= 1.16)
    rspec (2.5.0)
      rspec-core (~> 2.5.0)
      rspec-expectations (~> 2.5.0)
      rspec-mocks (~> 2.5.0)
    rspec-core (2.5.1)
    rspec-expectations (2.5.0)
      diff-lcs (~> 1.1.2)
    rspec-instafail (0.1.7)
    rspec-mocks (2.5.0)
    rspec-rails (2.5.0)
      actionpack (~> 3.0)
      activesupport (~> 3.0)
      railties (~> 3.0)
      rspec (~> 2.5.0)
    ruby-progressbar (0.0.9)
    ruby_parser (2.0.6)
      sexp_processor (~> 3.0)
    rubyzip (0.9.4)
    selenium-webdriver (0.1.3)
      childprocess (~> 0.1.5)
      ffi (~> 0.6.3)
      json_pure
      rubyzip
    sexp_processor (3.0.5)
    sinatra (1.2.0)
      rack (~> 1.1)
      tilt (< 2.0, >= 1.2.2)
    sqlite3 (1.3.3)
    sqlite3-ruby (1.3.3)
      sqlite3 (>= 1.3.3)
    sys-uname (0.8.5)
    term-ansicolor (1.0.5)
    thor (0.14.6)
    tilt (1.2.2)
    treetop (1.4.9)
      polyglot (>= 0.3.1)
    tzinfo (0.3.25)
    unicorn (3.5.0)
      kgio (~> 2.3)
      rack
    vegas (0.1.8)
      rack (>= 1.0.0)
    warden (1.0.3)
      rack (>= 1.0.0)
    watchr (0.7)
    wirble (0.1.3)
    xml-simple (1.0.14)
    xpath (0.1.3)
      nokogiri (~> 1.3)

PLATFORMS
  ruby

DEPENDENCIES
  SystemTimer
  ZenTest
  annotate
  autotest-fsevent
  autotest-growl
  autotest-rails-pure
  awesome_print
  aws-s3
  cancan
  capybara
  compass
  cucumber
  cucumber-rails
  dalli
  database_cleaner
  devise
  devise_invitable
  factory_girl_rails
  fastercsv
  formtastic
  fuubar
  fuubar-cucumber
  haml
  heroku
  heroku_san
  jquery-rails (>= 0.2.6)
  json
  launchy
  paperclip
  pg
  pickle
  rails
  rails_best_practices
  resque
  rspec
  rspec-core
  rspec-rails
  sitemap_generator!
  sqlite3-ruby
  unicorn
  watchr
  wirble

Gemfile.rb

source 'http://rubygems.org'

# ah-yup.
gem 'rails'
gem 'sqlite3-ruby'

# app server
gem 'unicorn'

# our beloved host
gem 'heroku'

# well. json
gem 'json'

# memcached library
gem 'dalli'

# background jobs
gem 'SystemTimer'
gem 'resque'

# csv processing
gem 'fastercsv'

# generate a sitemap and ping search servics to get indexed
gem 'sitemap_generator', :git => 'git://github.com/just3ws/sitemap_generator.git', :branch => 'heroku'

group :production do
  gem 'pg'
end

# authentication
gem 'devise'

# generating users
gem 'devise_invitable'

# authorization permissions
gem 'cancan'

# for Sass 
gem 'compass'

# form generation
gem 'formtastic'

# using jQuery instead of prototype/scriptaculous
gem 'jquery-rails', '>= 0.2.6'

# cleaner HTML
gem 'haml'

# for Amazon Web Service (S3)
gem 'aws-s3', :require => 'aws/s3'

# for dealing with physical files
gem 'paperclip'

group :development, :test do
  # simplify management of heroku environments 
  gem 'heroku_san'

  # given/when/then
  gem 'cucumber'
  gem 'cucumber-rails'

  # it should
  gem 'rspec-core' # I added it but it doesn't seem to help.
  gem 'rspec'
  gem 'rspec-rails'

  # factories
  gem 'factory_girl_rails'

  # automate the ui
  gem 'capybara'

  # cleans the database after tests
  gem 'database_cleaner'
  
  # And show me the page
  gem 'launchy'

  # model building
  gem 'pickle'

  # much improved test progress and fail-fast
  gem 'fuubar'
  gem 'fuubar-cucumber'

  # understand hotspots in the codebase
  gem 'rails_best_practices'

  # adds attribute and type docs to models and routes
  gem 'annotate'

  # run tests automatically
  gem "ZenTest"
  gem "autotest-rails-pure"
  gem 'watchr'

  if RUBY_PLATFORM =~ /darwin/
    gem "autotest-growl"
    gem "autotest-fsevent" 
  end
end

group :development do
  # improve Irb
  gem 'wirble'

  # better than pp
  gem 'awesome_print'
end

Notes

I've even gone so far as to destroy my RVM gemset and rebuild the gems. No luck. 

The problem only manifests when I run "rake" or "rake spec". If I run "rspec spec" it works fine, or even if I copy out the command that Rake was attempting to execute and run it directly it works fine. The failure only happens when I'm running via Rake.

RSpec via Rake error.sh

➜  ccs git:(master) ✗ rake --trace
(in /Users/mdh/src/project/ccs)
** Invoke default (first_time)
** Invoke spec (first_time)
** Invoke db:test:prepare (first_time)
** Invoke db:abort_if_pending_migrations (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute db:abort_if_pending_migrations
** Execute db:test:prepare
** Invoke db:test:load (first_time)
** Invoke db:test:purge (first_time)
** Invoke environment 
** Execute db:test:purge
** Execute db:test:load
** Invoke db:schema:load (first_time)
** Invoke environment 
** Execute db:schema:load
** Execute spec
/Users/mdh/.rvm/rubies/ruby-1.8.7-p334/bin/ruby -S bundle exec rspec ./spec/controllers/submissions_controller_spec.rb ./spec/controllers/users_controller_spec.rb ./spec/lib/generator_spec.rb
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@ccs/gems/bundler-1.0.10/lib/bundler/shared_helpers.rb:107:in `gem': rspec-core is not part of the bundle. Add it to Gemfile. (Gem::LoadError)
	from /Users/mdh/.rvm/gems/ruby-1.8.7-p334@ccs/bin/rspec:18
rake aborted!
ruby -S bundle exec rspec ./spec/controllers/submissions_controller_spec.rb ./spec/controllers/users_controller_spec.rb ./spec/lib/generator_spec.rb failed
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@ccs/gems/rspec-core-2.5.1/lib/rspec/core/rake_task.rb:139:in `initialize'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:1112:in `verbose'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@ccs/gems/rspec-core-2.5.1/lib/rspec/core/rake_task.rb:131:in `send'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@ccs/gems/rspec-core-2.5.1/lib/rspec/core/rake_task.rb:131:in `initialize'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:636:in `call'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:636:in `execute'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:631:in `each'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:631:in `execute'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:597:in `invoke_with_call_chain'
/Users/mdh/.rvm/rubies/ruby-1.8.7-p334/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:590:in `invoke_with_call_chain'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:607:in `invoke_prerequisites'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:604:in `each'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:604:in `invoke_prerequisites'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:596:in `invoke_with_call_chain'
/Users/mdh/.rvm/rubies/ruby-1.8.7-p334/lib/ruby/1.8/monitor.rb:242:in `synchronize'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:590:in `invoke_with_call_chain'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:583:in `invoke'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:2051:in `invoke_task'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:2029:in `top_level'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:2029:in `each'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:2029:in `top_level'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:2023:in `top_level'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:2001:in `run'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/lib/rake.rb:1998:in `run'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/gems/rake-0.8.7/bin/rake:31
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/bin/rake:19:in `load'
/Users/mdh/.rvm/gems/ruby-1.8.7-p334@global/bin/rake:19
➜  ccs git:(master) ✗