Use a very basic heuristic to find possible conflicting PRs
Don't log all possible conflicts

Amongst other things it avoids s Flake8 error:
scc/git.py:1355:1: C901 'GitRepository.merge' is too complex (14)
Add a test for listing changed files
Changed comment format
If no conflicts found then suggest a rebase
Use Python 2.6 set initialisation
merge master -D org: PR 181 (Try to fix intermittent SSL error in RebaseTest.has_rebased_pr())
merge master -D org: PR 186 (Comment on possible conflicts)
merge master -D org

Repository: openmicroscopy/snoopycrimecop
Already up-to-date.

Merged PRs:
  # PR 181 sbesson 'Try to fix intermittent SSL error in RebaseTest.has_rebased_pr()'
  # PR 186 manics 'Comment on possible conflicts'

Generated by SCC-merge#399 (http://ci.openmicroscopy.org/job/SCC-merge/399/)