use __gitdir for detecting git rep

bashrc

@@ -572,9 +572,8 @@ GIT_PS1_SHOWUPSTREAM=t
 __my_ps1_git(){
     local last=$?
     null type __git_ps1 || return $last
-    null git status || return $last # __gitdir seems to be able to be used
-    #test -n "`git status -s -uno`" && local star=\* # done by SHOWDIRTYSTATE
-    __git_ps1 "[GIT:$(__try_exec git config --get user.name):%s${star}]"
+    null __gitdir || return $last
+    __git_ps1 "[GIT:$(__try_exec git config --get user.name):%s]"
     return $last
 }
 __my_ps1_ipaddr(){