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.

--
A dir/b.o
? a.c
? a.o
? dir/c.o
? syntax
--
abort: .hgignore: invalid pattern (relre): *.o
--
A dir/b.o
? .hgignore
? a.c
? syntax
--
.hgignore: ignoring invalid syntax 'invalid'
A dir/b.o
? .hgignore
? a.c
? a.o
? dir/c.o
? syntax
--
A dir/b.o
? .hgignore
? a.c
? syntax
--
A dir/b.o
? .hgignore
? a.c
? a.o
? dir/c.o
--
A dir/b.o
--
A b.o