ci: Refactor mksnapshot test so that it doesn't stall. (#16875)

script/verify-mksnapshot.py

@@ -39,7 +39,7 @@ def main():
             + context_snapshot
 
       test_path = os.path.join(SOURCE_ROOT, 'spec', 'fixtures', \
-                               'snapshot-items-available.js')
+                               'snapshot-items-available')
 
       if sys.platform == 'darwin':
         bin_files = glob.glob(os.path.join(app_path, '*.bin'))
@@ -64,7 +64,7 @@ def main():
   except KeyboardInterrupt:
     print 'Other error'
     returncode = 0
-
+  print 'Returning with error code: {0}'.format(returncode)
   return returncode