[fish] Fix <C-t> completion for current dir search (#946)

If "." is given as the argument to begin <C-t> completion, the leading
"." is not correctly removed. In general, if user selects a fzf
completion, the current token should be "consumed".

shell/key-bindings.fish

@@ -29,9 +29,7 @@ function fzf_key_bindings
     if [ -z "$result" ]
       commandline -f repaint
       return
-    end
-
-    if [ "$dir" != . ]
+    else
       # Remove last token from commandline.
       commandline -t ""
     end