manifest: change manifestctx to not inherit from manifestdict If manifestctx inherits from manifestdict, it requires some weird logic to lazily load the dict if a piece of information is asked for. This ended up being complicated and unintuitive to use. Let's move the dict creation to .read(). This will make even more sense once we start adding readdelta() and other similar methods to manifestctx.

--- a/mercurial/context.py	Mon Sep 12 14:29:09 2016 -0700
+++ b/mercurial/context.py	Mon Sep 12 10:55:43 2016 -0700
@@ -528,7 +528,7 @@
 
     @propertycache
     def _manifest(self):
-        return self._repo.manifestlog[self._changeset.manifest]
+        return self._repo.manifestlog[self._changeset.manifest].read()
 
     @propertycache
     def _manifestdelta(self):