Fix passing shell var to awk; add 'develop' branch to whitelist

.gitconfig

@@ -49,8 +49,9 @@
     # Delete all remote refs that have been merged into the current branch.
     # Usage: git deleteremote <remote-name>
     deleteremote = "!sh -c 'git branch -r --merged \
-        | awk -F/ '\\''/^ *${1}/ && !/master/ { print \"refs/heads/\" $2 }'\\'' \
-        | xargs -p git push ${1} --delete' -"
+        | awk -F/ -v remote=${1:?Missing remote name.} \
+            '\\''$0 ~ remote && !/(master|develop)/ { print \"refs/heads/\" $2 }'\\'' \
+        | xargs -p -r git push ${1} --delete' -"
 
     l = log --format=format:'%C(auto)%h%d%C(reset) %s %C(bold blue)(%an, %ar)%C(reset)'
     ll = log --stat --decorate --abbrev-commit --date=relative