This should work:
WIKIMEDIA_REPOS=/path/where/you/have/your/clones REPO=$1 # qa/browsertests PULL=$2 # https://github.com/brainwane/qa-browsertests.git
TEMP=`mktemp --tmpdir -d pull-request.XXXXXXX` git clone --reference="$WIKIMEDIA_REPOS/$REPO" "$PULL" "$TEMP" cd "$TEMP"
if [ ! -f .gitreview ]; then cat > .gitreview <<EOF [gerrit] host=gerrit.wikimedia.org port=29418 project=$REPO.git defaultbranch=master defaultrebase=0 EOF fi
git-review -R
rm -rf "$TEMP"