Tor describes HTTPS proxy 403 errors as 'unexpected status code'
When Tor tries to connect to a relay or bridge through an HTTPS proxy, and the CONNECT request is rejected with a 403 error code (meaning 'Forbidden'), Tor describes the 403 response as an 'unexpected status code'. 403 errors should be logged with a more correct/useful message, and there are probably other error codes we should describe better as well.
For 403 errors, we could log
"... proxy refused to allow connection to %s".