git cl status: Force description encoding to utf-8 to avoid throwing

Example error: https://gist.github.com/danbeam/3c6b1f98b5d4a921a583a6f070ed0bf0

R=dpranke@chromium.org
BUG=none

Change-Id: Ib3406ce04782b08b1761506b494b96a827fa4a84
Reviewed-on: https://chromium-review.googlesource.com/c/1299615
Commit-Queue: Dan Beam <dbeam@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>

git_cl.py

@@ -2385,7 +2385,8 @@ class _GerritChangelistImpl(_ChangelistCodereviewBase):
     data = self._GetChangeDetail(['CURRENT_REVISION', 'CURRENT_COMMIT'],
                                  no_cache=force)
     current_rev = data['current_revision']
-    return data['revisions'][current_rev]['commit']['message']
+    return data['revisions'][current_rev]['commit']['message'].encode(
+        'utf-8', 'ignore')
 
   def UpdateDescriptionRemote(self, description, force=False):
     if gerrit_util.HasPendingChangeEdit(