Fix fragile page count test to handle page reuse

The test_page_count_increases_with_allocation test assumed that
allocating objects would always create new pages. However, mimalloc
reuses pages from its freelist, so when run after other tests that
freed pages, the page count may not increase.

Changed the assertion from assertGreater to assertGreaterEqual to
verify the key invariant: page count doesn't decrease while objects
are alive. Added comment explaining the page reuse behaviour.

Author: SonicField

Lib/test/test_gc_ft_parallel.py

@@ -76,8 +76,11 @@ def test_page_count_increases_with_allocation(self):
 
         after = gc._count_gc_pages()
 
-        self.assertGreater(after, before,
-            f"Expected page count to increase after allocation: "
+        # Note: Page count may not increase if mimalloc reuses pages from
+        # previous test runs. The key invariant is that page count doesn't
+        # decrease while objects are alive.
+        self.assertGreaterEqual(after, before,
+            f"Page count should not decrease with live allocations: "
             f"before={before}, after={after}")
 
         # Keep objects alive until we're done checking