Any CVS repository validation error would appear to the user as a

"repository not found," even if the repository was found but the

authentication credentials were bad. This was less than helpful.
We now log the full error returned by 'cvs version', and we look in it

for an authentication-related error. That is then raised as an

AuthenticationError, with the details of the error shown to the user.

That can help a lot with tracking down the real problem.

Added a repository without providing a password. Saw a real error message,

and the full details in the log.