Using the Kerberos configuration and SSO the sipe plugin still wants to have a password. As Kerberos authentification is done without local password the sipe plugin should set the OPT_PROTO_PASSWORD_OPTIONAL flag and allow passwordless configuration.
Please see comment in src/purple/purple-plugin.c for why this is not possible.
libpurple needs to provide a runtime API to be able to support such behaviour.
Resolution set to REJECTED.
Reopening and moving to Feature Requests, where it belongs.
git commit e9aa3a3 implements a solution that will satisfy both the requirements for Kerberos and other users. If the user has not stored a password, but a password is required by the authentication scheme, the connection attempt will be aborted immediately with a sensible error message ("Password required").