float_divmod():  the code wasn't sick enough to stop the MS optimizer
from optimizing away mod's sign adjustment when mod == 0; so it got
the intended result only in the debug build.
diff --git a/Objects/floatobject.c b/Objects/floatobject.c
index 7e12a09..cdc9620 100644
--- a/Objects/floatobject.c
+++ b/Objects/floatobject.c
@@ -476,7 +476,7 @@
 		   fmod returns different results across platforms; ensure
 		   it has the same sign as the denominator; we'd like to do
 		   "mod = wx * 0.0", but that may get optimized away */
-		mod = 0.0;
+		mod *= mod;  /* hide "mod = +0" from optimizer */
 		if (wx < 0.0)
 			mod = -mod;
 	}