rust: improve the type on DirsMultiset::from_manifest It could only return an HgPathError, but we didn't express this in the type, so we needed some unreachable!()s. Now that is expressed in the type.

rust: don't escape spaces in regex Spaces are not in fact a regex special character, and escaping them is not correct.

rust-filepatterns: also normalize RelPath These patterns should be normalized too; this at least does no harm, and is necessary for proper status support.