convert/bzr: make it work with filemaps (
issue1631)
The bzr converter maintains a child -> parents mapping and drop entries
whenever a child is read. It does not work with filemaps, getchangedfiles() may
be called more than once when filtered files belong to merge revisions.
getchanges() still works that way but it is not clear whether a similar issue
can arise when interacting with merges.
(binary:application/octet-stream)