branchmap: update cache of 'unserved' filter on new changesets The `commitctx` and `addchangegroup` methods of repo upgrade branchcache after completion. This behavior aims to keep the branchcache in sync for read only process as hgweb. See ee317dbfb9d0 for details. Since changelog filtering is used, those calls only update the cache for unfiltered repo. One of no interest for typical read only process like hgweb. Note: By chance in basic case, `repo.unfiltered() == repo.filtered('unserved')` This changesets have the "unserved" cache updated instead. I think this is the only cache that matter for hgweb. We could imagine updating all possible branchcaches instead but: - I'm not sure it would have any benefit impact. It may even increase the odd of all cache being invalidated. - This is more complicated change. So I'm going for updating a single cache only which is already better that updating a cache nobody cares about. This changeset have a few expected impact on the testsuite are different cache are updated.

tests: make test-hgweb.t output stable Instability introduced in combination of a4d7fd7ad1f7 and e389a25e7e60.

hgweb: ensure _navseq yield strictly increasing numbers This is not hard and allows to drop hack in the customer code.