unix_convert seems to get things wrong when case sensitive = yes

[Richard Sharpe]

Hi,

If you set case_sensitive, unix_convert returns fairly quickly after 
failing to stat a path. It returns with bad_path set to False.

However, if it is asked to convert /some/path/to/a/file, and anyone of 
'some', 'path', 'to', or 'a' do not exist, it will return with the 
incorrect error, it seems.

Regards
-----
Richard Sharpe, rsharpe[at]ns.aus.com, rsharpe[at]samba.org, 
sharpe[at]ethereal.com, http://www.richardsharpe.com