Revert "Revert "cbuildbot: Remove --pre-cq.""

Reland this CL, now that it's been shown to have not been the cause.

This reverts commit bda572e1a1ce8dd525baab6b8c1d1334e7cafaeb.

Change-Id: I6e969061e1a7eea5241ae76a0fd25566c19cccef
Reviewed-on: https://chromium-review.googlesource.com/287870
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index 4365d9f..adc3f73 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -159,7 +159,7 @@
   Returns:
     True if the builder should be a distributed_builder
   """
-  if build_config['pre_cq'] or options.pre_cq:
+  if build_config['pre_cq']:
     return True
   elif not options.buildbot:
     return False
@@ -643,8 +643,6 @@
             "target is a cq target, and we're in buildbot mode."))
   group.add_option('--pass-through', dest='pass_through_args', action='append',
                    type='string', default=[])
-  group.add_remote_option('--pre-cq', action='store_true', default=False,
-                          help='Mark CLs as tested by the PreCQ on success.')
   group.add_option('--reexec-api-version', dest='output_api_version',
                    action='store_true', default=False,
                    help=('Used for handling forwards/backwards compatibility '