Add pre-push git hook to prevent fixup and squash commits from ending up in master

  o Minor features (developer tooling):

    - Provide git hook script to prevent "fixup!" and "squash!" commits from

      ending up in master. Closes ticket 27993.

#!/bin/sh

# git pre-push hook script to prevent "fixup!" and "squash!" commit

# from ending up in master, or in any branch if CUR_BRANCH check is removed.

# It is meant to be placed in .git/hooks directory.

#

# The following sample script was used as starting point:

# https://github.com/git/git/blob/master/templates/hooks--pre-push.sample

z40=0000000000000000000000000000000000000000

CUR_BRANCH=$(git rev-parse --abbrev-ref HEAD)

if [ "$CUR_BRANCH" != "master" ]

then

        exit 0

fi

echo "Running pre-push hook"

# shellcheck disable=SC2034

while read -r local_ref local_sha remote_ref remote_sha

do

	if [ "$local_sha" = $z40 ]

	then

		# Handle delete

		:

	else

		if [ "$remote_sha" = $z40 ]

		then

			# New branch, examine all commits

			range="$local_sha"

		else

			# Update to existing branch, examine new commits

			range="$remote_sha..$local_sha"

		fi

                # Check for fixup! commit

                commit=$(git rev-list -n 1 --grep '^fixup!' "$range")

		if [ -n "$commit" ]

		then

			echo >&2 "Found fixup! commit in $local_ref, not pushing"

			exit 1

		fi

                # Check for squash! commit

                commit=$(git rev-list -n 1 --grep '^squash!' "$range")

		if [ -n "$commit" ]

		then

			echo >&2 "Found squash! commit in $local_ref, not pushing"

			exit 1

		fi

	fi

done

exit 0