SCC assumes a PR's repo name is the same as upstream

[manics]

E.g. ome/ome-docker#1

upstream https://github.com/ome/docker/
PR branch: https://github.com/manics/omedocker/tree/remove_omedocker

2014-11-20 11:43:58,185 [     scc.git] DEBUG ## Unique users: set([u'manics'])
2014-11-20 11:43:58,185 [     scc.git] DEBUG Calling 'git remote add merge_manics git://github.com/manics/docker.git'
2014-11-20 11:43:58,188 [     scc.git] DEBUG Fetching remote merge_manics...
2014-11-20 11:43:58,189 [     scc.git] DEBUG Calling 'git fetch merge_manics'

2014-11-20 11:43:58,375 [     scc.git] DEBUG fatal: remote error: 
2014-11-20 11:43:58,375 [     scc.git] DEBUG   Repository not found.
2014-11-20 11:43:58,375 [   scc.merge] DEBUG Cleaning remote branches created for merging
2014-11-20 11:43:58,375 [     scc.git] DEBUG Calling 'git remote'
2014-11-20 11:43:58,378 [     scc.git] DEBUG Calling 'git remote rm merge_manics'

[sbesson]

See https://github.com/openmicroscopy/snoopycrimecop/blob/v0.6.3/scc/git.py#L1634. This method should likely be changed to store (user, repo) tuples using the PR information.