atproto: /hashtag bug fix, handle newlines

fixes https://console.cloud.google.com/errors/detail/COugjNSr9oCtfg;time=PT1H;locations=global?project=bridgy-federated

atproto.py

@@ -1124,6 +1124,9 @@ def poll_chat_task():
 def hashtag_redirect(hashtag):
     if (util.domain_from_link(request.host_url) ==
             f'{ATProto.ABBREV}{common.SUPERDOMAIN}'):
-        return redirect(f'https://bsky.app/search?q=%23{hashtag}')
+        try:
+            return redirect(f'https://bsky.app/search?q=%23{hashtag}')
+        except ValueError as e:
+            logging.warning(e)
 
     raise NotFound()

tests/test_atproto.py

@@ -2788,3 +2788,8 @@ Sed tortor neque, aliquet quis posuere aliquam […]
 
         resp = self.get('/hashtag/foo', base_url='https://web.brid.gy')
         self.assert_equals(404, resp.status_code)
+
+    def test_hashtag_with_newlines_error(self):
+        # https://console.cloud.google.com/errors/detail/COugjNSr9oCtfg;time=PT1H;locations=global?project=bridgy-federated
+        resp = self.get('/hashtag/x%0Ay', base_url='https://bsky.brid.gy')
+        self.assert_equals(404, resp.status_code)