This fixes a bug that Chris Mason found. As for a test case, I can't
think of one. It's a very weird case. Basically, if there is a file
listed as changed in the changelog entry, but not showing up in any
of the associated manifest entries, hg would abort when trying to
create a changeset. Now it just decides the file must not have any
versions relevant to the changeset.
#!/bin/sh
hg init
hg log
hg grep wah
hg manifest
hg verify