pre-upload.py: --pre-submit has no description

`pre-upload.py --pre-submit` failed printing commit description.

BUG=chromium:1060760
TEST=manually verified

Change-Id: I15eb3a9c41529c40a3ffa2ac28ff1b3bfc7d9ae3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/repohooks/+/2098999
Tested-by: LaMont Jones <lamontjones@chromium.org>
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Commit-Queue: LaMont Jones <lamontjones@chromium.org>
Auto-Submit: LaMont Jones <lamontjones@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index c0bd20b..f897ccc 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -2070,7 +2070,9 @@
   for i, commit in enumerate(commit_list):
     CACHE.clear()
 
-    desc = _get_commit_desc(commit)
+    # If run with --pre-submit, then commit is PRE_SUBMIT, and not a commit.
+    # Use that as the description.
+    desc = commit if commit == PRE_SUBMIT else _get_commit_desc(commit)
     print('[%s %i/%i %s] %s' %
           (color.Color(color.CYAN, 'COMMIT'), i + 1, commit_count, commit[0:12],
            desc.splitlines()[0]))