Dir() vs env.Dir() strangness

c SConscript

env = Environment()
env.Command('a','b','/bin/echo path %s'%env.Dir('#'))
env.Command('c','b','/bin/echo path %s'%env.Dir('#b'))
env.Command('d','b','/bin/echo path %s'%Dir('#d'))

output

scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
/bin/echo path /Users/bdbaddog/devel/scons/tmp/b
path /Users/bdbaddog/devel/scons/tmp/b
/bin/echo path /Users/bdbaddog/devel/scons/tmp/b/b
path /Users/bdbaddog/devel/scons/tmp/b/b
/bin/echo path .
path .
scons: done building targets.

SConstruct

SConscript('c/SConscript')