Use python instead of slow shell script on verify-commits

contrib/verify-commits/pre-push-hook.sh

@@ -12,9 +12,9 @@ while read LINE; do
     if [ "$4" != "refs/heads/master" ]; then
         continue
     fi
-    if ! ./contrib/verify-commits/verify-commits.sh $3 > /dev/null 2>&1; then
+    if ! ./contrib/verify-commits/verify-commits.py $3 > /dev/null 2>&1; then
         echo "ERROR: A commit is not signed, can't push"
-        ./contrib/verify-commits/verify-commits.sh
+        ./contrib/verify-commits/verify-commits.py
         exit 1
     fi
 done < /dev/stdin