Your bug report

#6273: dired-current-directory with `t' arg returns empty string in  top-level mount-point "/"

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 6273@debbugs.gnu.org.

-- 
6273: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=6273
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