My environment uses SVN+SSH with username and password instead of a private key.
I found that even after switching to the "enter credentials" page, I would get
an "authorization failed" error. I downloaded the code from FishEye and started
hacking away at it. Based on my debugging, the version of SVNKit you are
currently using wants the keyFile field (SubversionSCM:756) to be null if there
isn't one, not an empty file. When I replace keyFile with null, everything
works as expected. You might also want to watch the if statement above (740) -
my debugger showed that the FileItem is never null.

Odd: even after deleting the entire .hudson directory, once my authentication
info is stored, Hudson remembers it. Where else is it being maintained?