the empty string at the command line should give you no attributes,
but just pressing return at the prompt gives you default attributes
(edit_entry): only pick up values from the default principal if they
aren't set in the principal being edited
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@9473 ec53bebd-3082-4978-b11e-865c3cabbd6b