Autoroller: Skip commit if there are no DEPS changes.

tools_webrtc/autoroller/roll_deps.py

 #!/usr/bin/env python
 # Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 """Script to automatically roll dependencies in the WebRTC DEPS file."""
@@ skipping 454 matching lines @@
   new_cr_deps = ParseRemoteCrDepsFile(new_cr_rev)
   changed_deps = CalculateChangedDeps(webrtc_deps, new_cr_deps)
   clang_change = CalculateChangedClang(new_cr_rev)
   commit_msg = GenerateCommitMessage(current_cr_rev, new_cr_rev,
                                      current_commit_pos, new_commit_pos,
                                      changed_deps, clang_change)
   logging.debug('Commit message:\n%s', commit_msg)
 
   _CreateRollBranch(opts.dry_run)
   UpdateDepsFile(deps_filename, current_cr_rev, new_cr_rev, changed_deps)
-  _LocalCommit(commit_msg, opts.dry_run)
-  _UploadCL(opts.dry_run, opts.rietveld_email)
-  _SendToCQ(opts.dry_run, opts.skip_cq)
+  if _IsTreeClean():
+    logging.info("No DEPS changes detected, skipping CL creation.")
+  else:
+    _LocalCommit(commit_msg, opts.dry_run)
+    _UploadCL(opts.dry_run, opts.rietveld_email)
+    _SendToCQ(opts.dry_run, opts.skip_cq)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())