repository: update interface signature of narrowmatch()
This should have been part of
4fd0fac48922 (localrepo: allow
narrowmatch() to accept matcher to intersect with, 2018-09-28) and
41fcdfe3bfeb (narrow: allow repo.narrowmatch(match) to include exact
matches from "match", 2018-10-01).
Differential Revision: https://phab.mercurial-scm.org/D5466
narrow: when narrowing, write new narrowspec before removing revlogs
If revlogs were removed and then the process crashed before the
narrowspec was written, the repo would be corrupt.
Differential Revision: https://phab.mercurial-scm.org/D5467