bpo-39048: Look up __aenter__ before __aexit__ in async with (GH-17609)

* Reorder the __aenter__ and __aexit__ checks for async with
* Add assertions for async with body being skipped
* Swap __aexit__ and __aenter__ loading in the documentation
diff --git a/Misc/ACKS b/Misc/ACKS
index d3e683d..3e45d5d 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1219,6 +1219,7 @@
 Jon Oberheide
 Milan Oberkirch
 Pascal Oberndoerfer
+Géry Ogam
 Jeffrey Ollie
 Adam Olsen
 Bryan Olson