Debian bug #231229. In that bug, it has been analysed that while swat behave correctly by proposing "default case" only on a share basis, the documentation (at least the smb.conf man page) suggests that it can be set globally (just like other name mangling options). Peter Eisentraut confirmed with a glance at the code that the option is not registered as a global option (which is also confirmed by running testparm on a smb.conf file wontaining it in the global section). So, unless the option should be allowed as a global option (and thus, this bug would turn out to be a bug in the code), the documentaiton should probably be fixed.
Thanks, fixed. - John T.