perf-stream-consume: use the source repository config when applying
This might contains critical configuration for the benchmark, like enabling of
extensions like narrow.
#require emacs
$ emacs -q -no-site-file -batch -l $TESTDIR/../contrib/hg-test-mode.el \
> -f ert-run-tests-batch-and-exit
Running 1 tests (*) (glob)
passed 1/1 hg-test-mode--compilation-mode-support* (glob)
Ran 1 tests, 1 results as expected* (glob)