fastannotate: use repo.local()
This is the proper way to check whether we're dealing with a local
repository, since extensions should be coding to an interface and
not testing for exact types.
Differential Revision: https://phab.mercurial-scm.org/D4542
#
# Avoid interference from actual test env:
unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL