fixup! use setter for stats, handling main color

src/_pytest/terminal.py

@@ -370,7 +370,7 @@ def line(self, msg, **kw):
 
     def _add_stats(self, category: str, items: List) -> None:
         if category not in self.stats:
-            self.stats[category] = items
+            self.stats[category] = items[:]
             self._set_main_color()
         else:
             self.stats[category].extend(items)