Diffusion - upgrade exception error message to include hint to config option
Summary: Fixes T6419. Also, there was a question on T6419 about whether this was in a try catch block and it is... Its not clear to me what happens in the "timeout" case though?
Test Plan: looks nice
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T6419
Differential Revision: https://secure.phabricator.com/D10755