KSENROLL-11841 Add test case to replicate dataloss in CM contribution branch

After the conversion we have dataloss in the CM contribution branches.

Create a base patch of the sandbox_ksenroll-8475 branch at r53642 and create
a new unit test that will apply that patch and then run the KS importer for
r53643 and r53644.

The problem was that we were fetching branches based on the copyfrom version.

In some cases the branch might not have existed in the revision before that
revision (and the parent id would not be located properly).

The change is to always use the currentRevision when getting GitBranchData.

After rerunning the importer on the ks project there were 25 additional commits
which effected over 40,000 commits in total.