discovery: handle deletion of 'wireproto' module
Mercurial commit b4d85bc122bd. deleted the wireproto module and its
contents are now in various other modules, so we can not even do
unchecked imports of it now.
# 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