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templater: drop deprecated handling of KeyError from changeset_templater It's been superseded by 09cde75e0613 and the previous patch.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

pycompat: alias xrange to range in py3

pycompat: fix demand import handling of Queue When demandimport is enabled, simply importing a non existent module does not trigger ImportError, a property access is necessary.

util: use __code__ (available since py2.6)

templater: give better error message for invalid engine type Before, KeyError was caught at changeset_templater._show(), which said "no key named '%s'" as it was intended to catch the KeyError of unknown map key. Instead, we should catch KeyError explicitly for better error indication. For those who don't know what the template engine is (read "everyone"), it is hidden extension feature that allows switching template syntax in map file. See d8c5a7f25a40 for details.