filemerge: set default labels a little earlier
By setting the default labels a little earlier, we can rely on them
always being set, as far as I can tell. It may actually even be fine
to rely on that even if we don't set them earlier, but it makes more
sense to me to do it.
Differential Revision: https://phab.mercurial-scm.org/D12015
$ hg init
$ "$PYTHON" -c 'open("a", "wb").write(b"confuse str.splitlines\nembedded\rnewline\n")'
$ hg ci -Ama -d '1 0'
adding a
$ echo clean diff >> a
$ hg ci -mb -d '2 0'
$ hg diff -r0 -r1
diff -r 107ba6f817b5 -r 310ce7989cdc a
--- a/a Thu Jan 01 00:00:01 1970 +0000
+++ b/a Thu Jan 01 00:00:02 1970 +0000
@@ -1,2 +1,3 @@
confuse str.splitlines
embedded\r (no-eol) (esc)
newline
+clean diff