run-tests: introduce a `HGTEST_REAL_HG` variable for test
It turns out that currently, `hg` and `which hg` can point to different things
because `hg` is an alias… This is annoying because script and pieces of test
are unknowingly using the wrong `hg`.
We will fix it in another changeset. However some test actually need to use a
real `hg` binary and not some `chg` or `rhg` equivalent. So we introduce a new
variable with the right value and we put it to us in the appropriate location.
Differential Revision: https://phab.mercurial-scm.org/D11049
# Blacklist for a full testsuite run with fsmonitor enabled.
# Used by fsmonitor-run-tests.
# The following tests all fail because they either use extensions that conflict
# with fsmonitor, use subrepositories, or don't anticipate the extra file in
# the .hg directory that fsmonitor adds.
#### mainly testing eol extension
test-eol-add.t
test-eol-clone.t
test-eol-hook.t
test-eol-patch.t
test-eol-tag.t
test-eol-update.t
test-eol.t
test-eolfilename.t
#### mainly testing largefiles extension
test-issue3084.t
test-largefiles-cache.t
test-largefiles-misc.t
test-largefiles-small-disk.t
test-largefiles-update.t
test-largefiles-wireproto.t
test-largefiles.t
test-lfconvert.t
#### mainly testing nested repositories
test-nested-repo.t
test-push-warn.t
test-subrepo-deep-nested-change.t
test-subrepo-recursion.t
test-subrepo.t
#### fixing these seems redundant, because these don't focus on
#### operations in the working directory or .hg
test-debugextensions.t
test-extension.t
test-help.t