evolve: move if-else block under the right block
the index related if-else should be only executed when all three base, divergent
and other have different branch names.
I coded this last night and mistakenly mis-indented it. Caught when I was adding
more tests.
tests: make sure we don't result in commit messages conflict
Upcoming patches will introduce functionality of merging commit messages while
resolving content divergence which can lead to conflicts.
We don't want to test the conflicts scenario here, so let's make sure there are
no conflicts of commit messages in this test.