Skip commit message check for backports (#1697) (#1704)

(cherry picked from commit ea2b0ee)

Co-authored-by: Ryan Julian <ryanjulian@users.noreply.github.com>

scripts/check_commit_message

@@ -1,4 +1,5 @@
 #!/usr/bin/env python
+"""Checks that a commit message conforms the the style guide."""
 import sys
 
 # Get the commit message location
@@ -10,6 +11,10 @@ lines = list((line.rstrip() for line in open(commit_msg_filepath, 'r')))
 # Remove all commented lines
 lines = [line for line in lines if len(line) == 0 or line[0] != '#']
 
+# Skip if this is an automated backport
+if len(lines) >= 2 and 'cherry picked from commit' in lines[-2]:
+    sys.exit(0)
+
 exit_code = 0
 
 # Error: no commit message