Normalize authentication errors from SVN.
Review Request #6275 — Created Aug. 26, 2014 and submitted
When failing to authenticate with a repository, the SVN backends will
return an error of "callback_get_login required." This looks like a bug
in Review Board, but is actually just an error message meaning that the
credentials were bad.We now normalize these errors, converting them into an
authentication-related error. The SSL error handling code already did
this, but now all call sites use it.
Manually tested several of the call sites. Unfortunately, it's a bit
tricky writing unit tests for this right now.Unit tests pass.