matplotlib/matplotlib — pull request #2115 by mdboom (2013-06-03 13:14:40+00:00)
Title: Make setup work on platforms where multiprocessing does not (1.3.x version)

multiprocessing is used during setup to check the version of Gtk 3 installed (since importing Gtk2 and Gtk3 in the same process causes problems). On platforms where multiprocessing doesn't work, this check will just be skipped.