tests/helper-runtests.sh

context: handle stringified ints in revsymbol()

This patch copies the handling of stringified ints from changectx's
constructor. It then calls repo.__getitem__ with the int. Since that
method only interprets integers as revnums the first thing it does,
this will not be redoing any of the work already done. We leave the
old code in place so we can later deprecate it instead of breaking
extensions.

Differential Revision: https://phab.mercurial-scm.org/D3146

#
# Avoid interference from actual test env:

unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL