mypy: Correct SVN integration & satisfy strict-optional typing.
The commit_notice_destination return value was previously not
checked against None, which indicates no message should be sent.
@@ -66,6 +66,7 @@ message = "**{0}** committed revision r{1} to `{2}`.\n\n> {3}".format(
destination = config.commit_notice_destination(path, rev) # type: Optional[Dict[Text, Text]]
+if destination is not None:
message_data = {
"type": "stream",
"to": destination["stream"],
