Resolves: bug 476891
Bug Description: Replication: Server to Server Connection Error:
SASL(-1): generic failure: All-whitespace username.
Reviewed by: ???
Files: see diff
Fix Description: 1) SASL/DIGEST-MD5 needs both username and authid
2) The username and authid in this context are always a bind DN - they
must have the "dn:" prefix in order for the SASL mapping to work
3) gssapi (kerberos) sets both username and authid to NULL
Platforms tested: RHEL5
Flag Day: no
Doc impact: no