manifest: define and implement rev() on manifestlog Various code is accessing repo.manifestlog._revlog - a private attribute. This bypasses our interface and makes it difficult to implement non-revlog manifest storage. This commit adds a rev() method to the manifestlog interface and class and teaches callers to use it. Ideally this method wouldn't exist, as very few consumers should need to resolve the revision number of a manifest. Again, the primary goal of interface work is to establish and use interfaces first and to improve them later. Differential Revision: https://phab.mercurial-scm.org/D3882

--- a/mercurial/manifest.py	Mon Jul 02 11:14:13 2018 -0700
+++ b/mercurial/manifest.py	Wed Jul 04 12:12:49 2018 -0700
@@ -1348,6 +1348,9 @@
         self._dirmancache.clear()
         self._revlog.clearcaches()
 
+    def rev(self, node):
+        return self._revlog.rev(node)
+
 @interfaceutil.implementer(repository.imanifestrevisionwritable)
 class memmanifestctx(object):
     def __init__(self, manifestlog):