check for ".corp.google.com" suffix in FQDN for copyright hook

This will cause _check_google_copyright() to simply return if
the committer's fully qualified domain name does not end in
".corp.google.com". The idea is to enforce the check for Googlers
but avoid blocking partners and external contributors.

BUG=none
TEST=Tested manually using different arguments to endswith().

Change-Id: I2d36a62de9b0623b8b5960f2f36aa5d2d101f5fb
Reviewed-on: https://gerrit.chromium.org/gerrit/42792
Reviewed-by: David James <davidjames@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Commit-Queue: David Hendricks <dhendrix@chromium.org>
Tested-by: David Hendricks <dhendrix@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index 7990b34..60a772b 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -9,6 +9,7 @@
 import optparse
 import os
 import re
+import socket
 import sys
 import subprocess
 
@@ -365,6 +366,11 @@
   )
   FAIL_MSG = "Copyright must match"
 
+  # Avoid blocking partners and external contributors.
+  fqdn = socket.getfqdn()
+  if not fqdn.endswith(".corp.google.com"):
+    return None
+
   return _verify_header_content(commit, LICENSE_HEADER, FAIL_MSG)