commit: remove reverse search for copy source when not in parent (issue4476)
Previously, we had weird, nonsensical behavior when committing a file move
with a missing source. This removes that weird logic and tests that the bug
this strange behavior caused is fixed. Also adds a longish comment to prevent
some poor soul from accidentally re-implementing the bug in the future.
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ ls
a
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
B should disappear
$ ls
a