gitstats: Bugfix for branchContains Fix the branch
When re-using the code to get all branchnames and then
storing it as branchname/hash the %(objectname) was not
changed to %(refname), as a result the stored 'name' for
the hash was the hash itself.
This fixes that and also introduces a way to specify
multiple branches as branch-filter. In the proces it fixes
the bug caused by passing a string to set() where a array
with just one string should have been passed.
Bug-introduced-in:
af2fff8d9d6a7973a6b86ddac26188683a78a51a