tests: import mercurial modules by name in test-propertycache
This is our convention, and silences import-checker.py that would say
imports weren't lexically sorted.
tests: remove unused import of mercurial.repoview from test-propertycache
I don't see any reason to import it, but if there is a reason, please disregard
this and the next patch.
templater: drop deprecated handling of KeyError from changeset_templater
It's been superseded by
09cde75e0613 and the previous patch. templater.mapfile
is no longer used and removed.