URL for remote are too long for pip when caching is enabled

[alexd-siaras]

When acting as a caching proxy, the URLs referring to a remote proxy are very long. For example, python-saharaclient will yield the following URL: http://sheeva:8176/packages/source/p/python-saharaclient/python-saharaclient-0.7.0.tar.gz?remote=http%3A%2F%2Fpypi.python.org%2Fpackages%2Fsource%2Fp%2Fpython-saharaclient%2Fpython-saharaclient-0.7.0.tar.gz

When pip caching is enabled, the tarball will be attemped to be saved as: 'http%3A%2F%2Fsheeva%3A8176%2Fpackages%2Fsource%2Fp%2Fpython-saharaclient%2Fpython-saharaclient-0.7.0.tar.gz%3Fremote%3Dhttp%253A%252F%252Fpypi.python.org%252Fpackages%252Fsource%252Fp%252Fpython-saharaclient%252Fpython-saharaclient-0.7.0.tar.gz.content-type'

This file name is longer than the allowed 255 filename characters in most modern linux filesystems, and pip will result in an error:

2014-05-12 11:55:04.653 | Downloading/unpacking python-saharaclient>=0.6.0 (from tempest==2014.1.dev3940.g744617c)
2014-05-12 11:55:04.655 | Storing download in cache at /var/cache/pip/http%3A%2F%2Fsheeva%3A8176%2Fpackages%2Fsource%2Fp%2Fpython-saharaclient%2Fpython-saharaclient-0.7.0.tar.gz%3Fremote%3Dhttp%253A%252F%252Fpypi.python.org%252Fpackages%252Fsource%252Fp%252Fpython-saharaclient%252Fpython-saharaclient-0.7.0.tar.gz
2014-05-12 11:55:04.658 | Cleaning up...
2014-05-12 11:55:04.660 | Exception:
2014-05-12 11:55:04.663 | Traceback (most recent call last):
2014-05-12 11:55:04.666 | File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/basecommand.py", line 134, in main
2014-05-12 11:55:04.668 | status = self.run(options, args)
2014-05-12 11:55:04.671 | File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/commands/install.py", line 236, in run
2014-05-12 11:55:04.675 | requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
2014-05-12 11:55:04.677 | File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/req.py", line 1092, in prepare_files
2014-05-12 11:55:04.680 | self.unpack_url(url, location, self.is_download)
2014-05-12 11:55:04.683 | File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/req.py", line 1238, in unpack_url
2014-05-12 11:55:04.686 | retval = unpack_http_url(link, location, self.download_cache, self.download_dir)
2014-05-12 11:55:04.688 | File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/download.py", line 630, in unpack_http_url
2014-05-12 11:55:04.691 | cache_download(cache_file, temp_location, content_type)
2014-05-12 11:55:04.693 | File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/util.py", line 582, in cache_download
2014-05-12 11:55:04.695 | fp = open(target_file+'.content-type', 'w')
2014-05-12 11:55:04.698 | IOError: [Errno 36] File name too long: '/var/cache/pip/http%3A%2F%2Fsheeva%3A8176%2Fpackages%2Fsource%2Fp%2Fpython-saharaclient%2Fpython-saharaclient-0.7.0.tar.gz%3Fremote%3Dhttp%253A%252F%252Fpypi.python.org%252Fpackages%252Fsource%252Fp%252Fpython-saharaclient%252Fpython-saharaclient-0.7.0.tar.gz.content-type'

Now, granted that this is a limitation of pip, however if could be avoided if the "?remote" parameter did not contain the entire URL, but perhaps a hash of the remote URL.