depot_tools PRESUBMIT.py and tools/build PRESUBMIT.py both run on cq.golo.

If broken dev_appserver.py instances are left around, they will conflict with
master ports.

BUG=351926

Review URL: https://codereview.chromium.org/197073007

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@256721 0039d316-1c4b-4281-b951-d872f2087c98