only allow "forward" patches & exit 1 if virtualenv isn't found

setup_venv.sh

@@ -4,6 +4,7 @@ set -e
 
 if [ ! $venv ]; then
     echo "ERROR: virtualenv not found!" >&2
+    exit 1
 else
     if [ ! -d $venv_dir ] ; then
         $venv --distribute $venv_dir
@@ -12,5 +13,5 @@ else
     . $venv_dir/bin/activate
     pip install -r etc/reqs.txt
     # Apply multi-domain patch to Flask-Babel
-    patch -p0 <etc/multi-domain.patch
+    patch -p0 -N -r - <etc/multi-domain.patch
 fi