In nmbd we try to truncate the netbios name if we try to register it.
with commit d546adeab54af123eff66cee61a487c88b6ba61b the behaviour of push_ascii_nstring() changed.
This change of behaviour creates a bug in register_name(). If we call push_ascii_nstring() on a netbios name longer than 15 chars we end up registering an empty string!
To reprocude this set the following variable in smb.conf and start nmbd:
netbios name = XABCDEFGHIJKLMNOPQRSTUVWXYZ
X will be replaced by \0.
*** This bug has been marked as a duplicate of bug 10896 ***