Subversion tries to get passwords from gnome-keyring or kwallet, which screws things up badly when not running Gnome or KDE. To fix for the entire system, edit (as root) /etc/subversion/config (in Debian) to uncomment the "password-stores = ..." line and set it to null, i.e.,
password-stores =
To fix for one's own account, do the same thing in your home directory in
~/.subversion/config