Fix fish shell completion

cmd/install/fish.go

@@ -41,12 +41,12 @@ func (f fish) cmd(cmd, bin string) (string, error) {
 	params := struct{ Cmd, Bin string }{cmd, bin}
 	tmpl := template.Must(template.New("cmd").Parse(`
 function __complete_{{.Cmd}}
-    set -lx COMP_LINE (string join ' ' (commandline -o))
-    test (commandline -ct) = ""
+    set -lx COMP_LINE (commandline -cp)
+    test -z (commandline -ct)
     and set COMP_LINE "$COMP_LINE "
     {{.Bin}}
 end
-complete -c {{.Cmd}} -a "(__complete_{{.Cmd}})"
+complete -f -c {{.Cmd}} -a "(__complete_{{.Cmd}})"
 `))
 	err := tmpl.Execute(&buf, params)
 	if err != nil {