test-compat: merge mercurial-4.7 into mercurial-4.6

# no-check-commit

--HG--
branch : mercurial-4.6
4 jobs for topic/mercurial-4.6/release-prep in 3 minutes and 49 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #175081
doc

00:01:14

manual #175078
allowed to fail manual
pytype
passed #175079
tests-py2-cext

00:03:46

passed #175080
tests-py2-pure

00:03:49