tests: alias ui as uimod in test-revlog-ancestry/test-ui-verbosity

tests: move stdlib imports before mercurial modules in test-parseindex2

tests: stop direct symbol import of pprint.pprint in tests-minirst

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templater: drop deprecated handling of KeyError from changeset_templater It's been superseded by 09cde75e0613 and the previous patch.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.

test-commandserver: handle cStringIO.StringIO/io.StringIO divergence

pycompat: add util.stringio to handle py3 divergence util.stringio = cStringIO.StringIO / io.StringIO