Remove a comment in merge_tests.py 78 that has been wrong since the change made in r871974 ("Fix issue #3067, 'subtrees that don't exist at the start or end of a merge range shouldn't break the merge'").
* subversion/tests/cmdline/merge_tests.py (dont_merge_revs_into_subtree_that_predate_it): Remove a comment.
* subversion/tests/cmdline/merge_tests.py (avoid_reflected_revs): Tweak this XFAIL test to not expect conflicts, since the ideal result would be a clean merge. That expectation appears to have been set in error when I merged the tree-conflicts branch to trunk in r873156. Also improve the comments.