util._matcher: unify pattern normalization
This should fix issue347.
It also highlights one issue with the directory walking code when
you have an --include pattern that matches the end of a filename.
This is fixed by the next patch.
abort: repository a not found!
255
abort: error: Connection refused
255
abort: repository a not found!
255
abort: destination '../a' already exists
255
abort: repository a not found!
255
destination directory: q
abort: destination 'q' already exists