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/repository.py	Mon Jul 02 11:14:13 2018 -0700
+++ b/mercurial/repository.py	Wed Jul 04 12:12:49 2018 -0700
@@ -922,6 +922,12 @@
     def clearcaches():
         """Clear caches associated with this collection."""
 
+    def rev(node):
+        """Obtain the revision number for a binary node.
+
+        Raises ``error.LookupError`` if the node is not known.
+        """
+
 class completelocalrepository(interfaceutil.Interface):
     """Monolithic interface for local repositories.