Workaround difference between BSD and GNU seq in dirh

dirh still doesn't make any sense

share/functions/dirh.fish

@@ -26,9 +26,12 @@ function dirh --description "Print the current directory history (the back- and
 	echo -n -e $current$separator
 	set_color normal
     
+    # BSD seq 0 outputs '1 0' instead of nothing
+    if test (count $dirnext) -gt 0
         for i in (seq (echo (count $dirnext)) -1 1)
             echo -n -e $dirnext[$i]$separator
         end
+    end
 
 	echo
 end