tests: add a comment in a test that will hopefully save someone some time
I spent at least an hour, probably closer to 1.5, trying to figure out what this
was complaining about. Hopefully anyone else in my position will see this note
and not waste the time.
Differential Revision: https://phab.mercurial-scm.org/D9953
#require execbit
$ hg init repo
$ cd repo
$ echo foo > foo
$ chmod 644 foo
$ hg ci -qAm '644'
$ chmod 755 foo
$ hg ci -qAm '755'
reverting to rev 0
$ hg revert -a -r 0
reverting foo
$ hg st
M foo
$ hg diff --git
diff --git a/foo b/foo
old mode 100755
new mode 100644
$ cd ..