Remove duplicate assignment of same variable in presubmit code

Change-Id: I04261053a37db078e2aff579ab4521056cce673c
Reviewed-on: https://chromium-review.googlesource.com/931555
Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>

presubmit_support.py

@@ -137,8 +137,6 @@ class _PresubmitResult(object):
     """
     self._message = message
     self._items = items or []
-    if items:
-      self._items = items
     self._long_text = long_text.rstrip()
 
   def handle(self, output):