error

error.txt

-----> Fetching custom git buildpack... done
-----> Ruby/Rack app detected
-----> Vendoring binaries
 Fetching cairo-1.12.8.tgz
/tmp/build_2z0sqxbwxc8m1/vendor/cairo-1.12.8
 Exporting cairo-1.12.8.tgz build and include paths
 Fetching pixman-0.28.0.tgz
/tmp/build_2z0sqxbwxc8m1/vendor/pixman-0.28.0
 Exporting pixman-0.28.0.tgz build and include paths
-----> Using Ruby version: ruby-2.0.0
-----> WARNING: Removing `Gemfile.lock` because it was generated on Windows.
       Bundler will do a full resolve so native gems are handled properly.
       This may result in unexpected gem versions being used in your app.
-----> Installing dependencies using Bundler version 1.3.2
       Ruby version change detected. Clearing bundler cache.
       Old: ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux]
       New: ruby 2.0.0p195 (2013-05-14 revision 40734) [x86_64-linux]
       Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin
       Fetching gem metadata from https://rubygems.org/...........
       Fetching gem metadata from https://rubygems.org/..
       Resolving dependencies...
       Installing pkg-config (1.1.4)
       Installing cairo (1.12.6)
       Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
       /tmp/build_2z0sqxbwxc8m1/vendor/ruby-2.0.0/bin/ruby extconf.rb
       checking for GCC... yes
       checking for Win32 OS... no
       checking for cairo version (>= 1.2.0)... yes
       checking for Mac OS X... no
       checking for HAVE_RUBY_ST_H in ruby.h... yes
       checking for HAVE_RUBY_IO_H in ruby.h... yes
       checking for rb_errinfo() in ruby.h... no
       checking for enum ruby_value_type in ruby.h... yes
       creating Makefile
       make
       compiling rb_cairo_constants.c
       rb_cairo_constants.c: In function ‘rb_cairo_operator_from_ruby_object’:
       rb_cairo_constants.c:152: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_antialias_from_ruby_object’:
       rb_cairo_constants.c:153: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_fill_rule_from_ruby_object’:
       rb_cairo_constants.c:154: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_line_cap_from_ruby_object’:
       rb_cairo_constants.c:155: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_line_join_from_ruby_object’:
       rb_cairo_constants.c:156: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_font_slant_from_ruby_object’:
       rb_cairo_constants.c:157: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_font_weight_from_ruby_object’:
       rb_cairo_constants.c:158: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_subpixel_order_from_ruby_object’:
       rb_cairo_constants.c:159: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_hint_style_from_ruby_object’:
       rb_cairo_constants.c:160: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_hint_metrics_from_ruby_object’:
       rb_cairo_constants.c:161: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_path_data_type_from_ruby_object’:
       rb_cairo_constants.c:162: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_extend_from_ruby_object’:
       rb_cairo_constants.c:165: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_filter_from_ruby_object’:
       rb_cairo_constants.c:166: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_svg_version_from_ruby_object’:
       rb_cairo_constants.c:168: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_ps_level_from_ruby_object’:
       rb_cairo_constants.c:173: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_pdf_version_from_ruby_object’:
       rb_cairo_constants.c:180: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_text_cluster_flags_from_ruby_object’:
       rb_cairo_constants.c:186: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_script_mode_from_ruby_object’:
       rb_cairo_constants.c:190: warning: comparison of unsigned expression < 0 is always false
       rb_cairo_constants.c: In function ‘rb_cairo_region_overlap_from_ruby_object’:
       rb_cairo_constants.c:194: warning: comparison of unsigned expression < 0 is always false
       compiling rb_cairo_context.c
       compiling rb_cairo_private.c
       rb_cairo_private.c: In function ‘rb_cairo__invoke_callback’:
       rb_cairo_private.c:226: error: ‘ruby_errinfo’ undeclared (first use in this function)
       rb_cairo_private.c:226: error: (Each undeclared identifier is reported only once
       rb_cairo_private.c:226: error: for each function it appears in.)
       make: *** [rb_cairo_private.o] Error 1
       Gem files will remain installed in /tmp/build_2z0sqxbwxc8m1/vendor/bundle/ruby/2.0.0/gems/cairo-1.12.6 for inspection.
       Results logged to /tmp/build_2z0sqxbwxc8m1/vendor/bundle/ruby/2.0.0/gems/cairo-1.12.6/ext/cairo/gem_make.out
       An error occurred while installing cairo (1.12.6), and Bundler cannot continue.
       Make sure that `gem install cairo -v '1.12.6'` succeeds before bundling.
 !
 !     Failed to install gems via Bundler.
 !

 !     Push rejected, failed to compile Ruby/Rack app

To git@heroku.com:tenkigirls-lingrbot.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'git@heroku.com:tenkigirls-lingrbot.git'

I am getting the same error, how did you solve this?