When a project is configured to include request-related information in a

format string, and something logs a message before that information is

set on the request, an exception is raised. This has occurred in various

setups in the past. It wasn't particularly common on Django 1.6, but it

happens any time there's a HTTP 404 on newer versions.
We now capture this and return an empty string for the request

information (just like we do if there's no request), avoiding this crash

and ensuring we log something useful.

Triggered a HTTP 404 on Django 1.11 and saw the exception raised, prior

to this patch. After the patch, a suitable statement was logged.
Standard logging with valid request info still works as expected.