make git prompt blue when clean repo with untracked files

functions/fish_prompt.fish

@@ -64,6 +64,9 @@ function fish_prompt
 
         else if git_is_touched
             set git_color white red
+
+        else if git_has_untracked
+            set git_color white blue
         end
 
         if git_is_detached_head

functions/git_has_untracked.fish

@@ -0,0 +1,3 @@
+function git_has_untracked -d "Test if there are any untracked files in the working tree"
+    test "0" != (git_untracked_files)
+end