Race condition when 2 projects share eggs-directory

[Ignas Mikalajūnas]

If you run bootstrap in 2 different projects that share the same eggs-directory at the same time, sometimes one of them crashes with this:

python2.5 bootstrap.py
Downloading http://pypi.python.org/packages/2.5/s/setuptools/setuptools-0.6c11-py2.5.egg
Creating directory '/srv/en.u2ti.com/code/ututi2009-12-14_10-22-13/bin'.
Creating directory '/srv/en.u2ti.com/code/ututi2009-12-14_10-22-13/parts'.
Creating directory '/srv/en.u2ti.com/code/ututi2009-12-14_10-22-13/develop-eggs'.
While:
  Bootstrapping.

An internal error occured due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
  File "/tmp/tmpISF7-w/zc.buildout-1.4.3-py2.5.egg/zc/buildout/buildout.py", line 1660, in main
    getattr(buildout, command)(args)
  File "/tmp/tmpISF7-w/zc.buildout-1.4.3-py2.5.egg/zc/buildout/buildout.py", line 357, in bootstrap
    shutil.copytree(dist.location, dest)
  File "/usr/lib/python2.5/shutil.py", line 115, in copytree
    os.makedirs(dst)
  File "/usr/lib/python2.5/os.py", line 171, in makedirs
    mkdir(name, mode)
OSError: [Errno 17] File exists: '/home/ututi/.buildout/eggs/zc.buildout-1.4.3-py2.5.egg'