Fix broken pipe error

Author: rbanka1

check_license/check_headers.sh

@@ -71,7 +71,8 @@ if [ $CHECK_ALL -eq 0 ]; then
 	CURRENT_COMMIT=$($GIT log --pretty=%H -1)
 	MERGE_BASE=$($GIT merge-base HEAD origin/master 2>/dev/null)
 	[ -z $MERGE_BASE ] && \
-		MERGE_BASE=$($GIT log --pretty="%cN:%H" | grep GitHub | head -n1 | cut -d: -f2)
+		LOG_OUTPUT=$($GIT log --pretty="%cN:%H")
+		MERGE_BASE=$(echo "$LOG_OUTPUT" | grep GitHub | head -n1 | cut -d: -f2)
 	[ -z $MERGE_BASE -o "$CURRENT_COMMIT" = "$MERGE_BASE" ] && \
 		CHECK_ALL=1
 fi