topic: reorder revset for faster evaluation
When running the revset on unfiltered repository, the mutable set can get huge.
So removing the obsolete changeset first provide a large speedup. This resolve
the performance regression we were seeing since the 6.7.0 release.
# utility to setup pythonpath to point into the tested repository
export SRCDIR=`dirname $TESTDIR`
if [ -n "$PYTHONPATH" ]; then
export HGTEST_ORIG_PYTHONPATH=$PYTHONPATH
export PYTHONPATH=$SRCDIR:$PYTHONPATH
else
export PYTHONPATH=$SRCDIR
fi