Revert the Lib/test/test_bigmem.py changes from commit 17891566a478 (and a
few other assertEqual tests that snuck in), and expand the docstrings and
comments explaining why and how these tests are supposed to work.
diff --git a/Lib/test/support.py b/Lib/test/support.py
index 52ec232..fbf6de4 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -1029,6 +1029,11 @@
     return decorator
 
 def precisionbigmemtest(size, memuse):
+    """Decorator for bigmem tests that need exact sizes.
+
+    Like bigmemtest, but without the size scaling upward to fill available
+    memory.
+    """
     def decorator(f):
         def wrapper(self):
             size = wrapper.size