tests/helper-runtests.sh

tests: add test for issue5343 (grafting with copies)

It seems that issue5353 resulted in a lot of tests in test-graft.t,
but the bug actually reported in that issue didn't get a test
case. This patch adds one for the "move" and one for the "copy"
version of it. I also added a "copy+modify" case, to show what should
be a merge conflict. I didn't add one for the "backwards" version of
it since the comment says that that was already covered by previous
work.

The tests added by this patch show the broken behavior (the bug is
still open). I suspect the results returned from mergecopies() are not
expressive enough to fix this issue: it has a dict for copies to merge
with, but that can only give one more filename, but here we need two
(one for the path on the remote side and one for the path in the merge
base). I want to have it tested anyway since I'm about to refactor
mergecopies().

Differential Revision: https://phab.mercurial-scm.org/D6242

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL