pre-receive hook with minor changes

pre-receive hook

#/bin/bash

# Copyright (c) 2016 G. Sylvie Davies. http://bit-booster.com/
# Copyright (c) 2016 torek. http://stackoverflow.com/users/1256452/torek
# License: MIT license. https://opensource.org/licenses/MIT
while read oldrev newrev refname
do
if [[ "$refname" == "refs/heads/master" ]]; then
   MATCH=`git log --first-parent --pretty='%P' $oldrev..$newrev |
     grep $oldrev |
     awk '{ print \$1 }'`

   if [[ "$oldrev" == "$MATCH" ]]; then
     exit 0
   else
     echo 1>&2 "*** PUSH REJECTED! FOXTROT MERGE BLOCKED!!! ***"
     exit 1
   fi
fi
done