Maintain invariant of maxsize items in cache attribute in MultiHitLRUCache

This minor change ensures the cache never has more than `maxsize`
items in `cache`. The previous implementation would temporarily
exceed `maxsize` items by one item when the cache adds the
newest entry to `cache` before removing the least recently used
item from `cache` with `self.cache.popitem(last=False)`.

Author: shailshouryya

Doc/library/collections.rst

@@ -1260,9 +1260,9 @@ variants of :func:`functools.lru_cache`:
             else:
                 # entry has been seen more than cache_after times
                 self.requests.pop(args) # no longer need to keep track of how many times this entry has been seen
-                self.cache[args] = result
-                if len(self.cache) > self.maxsize:
+                if len(self.cache) == self.maxsize:
                     self.cache.popitem(last=False)
+                self.cache[args] = result
             return result
 
 .. doctest::