fix_lib64 breaks running virtualenv on top of a virtualenv directory.

[oremj]

#rm -rf /tmp/venv
#virtualenv /tmp/venv
New python executable in /tmp/venv/bin/python
Installing setuptools............done.
Installing pip...............done.
#virtualenv /tmp/venv
Traceback (most recent call last):
  File "/usr/bin/virtualenv", line 9, in <module>
    load_entry_point('virtualenv==1.8.2', 'console_scripts', 'virtualenv')()
  File "/usr/lib/python2.6/site-packages/virtualenv.py", line 942, in main
    never_download=options.never_download)
  File "/usr/lib/python2.6/site-packages/virtualenv.py", line 1043, in create_environment
    site_packages=site_packages, clear=clear))
  File "/usr/lib/python2.6/site-packages/virtualenv.py", line 1186, in install_python
    fix_lib64(lib_dir)
  File "/usr/lib/python2.6/site-packages/virtualenv.py", line 1564, in fix_lib64
    os.path.join(os.path.dirname(lib_parent), 'lib64'))
OSError: [Errno 17] File exists

The function just needs to check for existence of an existing symlink.

[chrisspen]

This is still broken in the 1.8.2 release.

[carljm]

Yes, that's correct, it was fixed after that release.

Check on "develop" branch - if it's still broken for you there, we can reopen.