Comment 1 for bug 1007110

I reckon this is because of the --use-mirrors option, combined with the fact that pip does not try the right link at the first attempt.
See here verbose pip output: http://paste.openstack.org/show/18671/

pip tries a given download link on all the mirrors before choosing a different link. As there are thousands of mirrors, this explains why the process appears to be stuck.

^C does not help, or at least helps very little, as the only effects it has it to force skip of the current mirror and move to the next one. I have removed --use-mirrors from the pip install cmdline, but I reckon this cannot be considered a satisfactory fix.