in 1.8.3, using --distribute fails when distribute is installed as egg directory

[qwcode]

assuming you have distribute installed as an egg dir, you get this error trying to use --distribute

~$ virtualenv venv --distribute
   ...snip...
  OSError: Command /home/qwcode/d/bin/python -c "# Called from virtua...main(sys.argv[1:])
 " /usr/local/lib/pytho...ute-0.6.28-py2.6.egg failed with error code 1

the problem arises from this change: e8fbbea

it's trying to look for distribute egg files to install from and finds the distribute egg directory.

these errors are showing in the pip travis builds: https://travis-ci.org/pypa/pip/jobs/3335283

[qwcode]

fyi @pfmoore

[qwcode]

@pnasrat , I think this means a 1.8.4, see pull #362 for a fix.