Renato Cunha <renato@renatocunha.com> [Wed, 14 Dec 2011 12:28:00 -0200] rev 15634
diff: don't crash when diffing a revision with a deleted subrepo (issue3153)
When a user requested a diff between a revision (r1) that contained a subrepo
and another (r2) that did not, mercurial would crash if r1 was specified before
r2 but would execute the diff otherwise. This fixes this behavior by skipping
the missing subrepo in the diff.