Fix cherry-picking in a non-git environment.

None was always passed to urlparse causing "Unable to determine host" error.

Bug: b/391547354
Change-Id: I58b63b4a33135952cae102e8446eea7cb3a82531
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6226685
Commit-Queue: Gennady Tsitovich <gtsitovich@google.com>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

git_cl.py

@@ -4587,7 +4587,7 @@ def CMDcherry_pick(parser, args):
     host = None
     if options.host:
         try:
-            host = urllib.parse.urlparse(host).hostname
+            host = urllib.parse.urlparse(options.host).hostname
         except ValueError as e:
             print(f'Unable to parse host: {host}. Error: {e}', file=sys.stderr)
             return 1