context: do not cache manifestctx

This will make sure when ctx.repo.manifestlog changes, a correct new
manifestctx is returned. repo.manifestlog takes care of caching so the
manifestctx won't be reconstructed every time.

mercurial/context.py

@@ -551,7 +551,7 b' class changectx(basectx):'
     def _manifest(self):
         return self._manifestctx.read()
 
-    @propertycache
+    @property
     def _manifestctx(self):
         return self._repo.manifestlog[self._changeset.manifest]
 
@@ -2314,7 +2314,7 b' class metadataonlyctx(committablectx):'
     def manifestnode(self):
         return self._manifestnode
 
-    @propertycache
+    @property
     def _manifestctx(self):
         return self._repo.manifestlog[self._manifestnode]
 

tests/test-context.py.out

@@ -47,6 +47,4 b" wcctx._status=<status modified=['bar-m']"
 == commit with manifestlog invalidated
 commit 1: 2efe531a913fa648867ab8824360371679d05a65
 commit 2: 2caca91f6362020334384ebe27bae67315298abf
-cannot read data: LookupError('Q\xa3L\xa5Ou\x8f\xce8\xda<Q\x7f\x9f(\xc9;Li/', '00manifest.i', 'no node')
 commit 3: abd6b0f49f338be22b094ef2b7425e8048f8337b
-cannot read data: LookupError("\x82\x15\xb8\xd3\x85\xf6H'\x9cP'D\x97\x1e\xab\x98O\xbb\x05\x9d", '00manifest.i', 'no node')