bookmarks: remove changectx() method from bmstore (API)

All the callsites of this method have access to the repo, and I'd
rather not have to duplicate this across alternative bmstore
implementations. Besides, it feels like a bit of a layering violation.

.. api::

    `mercurial.bookmarks.bmstore` no longer has a convenience method
    for looking up changectx instances from a bookmark name. Use
    `repo[repo.bookmarks[name]]` intead of
    `repo.bookmarks.changectx(name)`.

Differential Revision: https://phab.mercurial-scm.org/D6884

hgext/infinitepush/bundleparts.py

@@ -12,6 +12,7 from mercurial import (
     changegroup,
     error,
     extensions,
+    node as nodemod,
     revsetlang,
     util,
 )
@@ -48,7 +49,7 def getscratchbranchparts(repo, peer, ou
         params['bookprevnode'] = ''
         bookmarks = repo._bookmarks
         if bookmark in bookmarks:
-            params['bookprevnode'] = bookmarks.changectx(bookmark).hex()
+            params['bookprevnode'] = nodemod.hex(bookmarks[bookmark])
 
     # Do not send pushback bundle2 part with bookmarks if remotenames extension
     # is enabled. It will be handled manually in `_push()`

mercurial/bookmarks.py

@@ -177,10 +177,6 class bmstore(object):
         """Return a sorted list of bookmarks pointing to the specified node"""
         return self._nodemap.get(node, [])
 
-    def changectx(self, mark):
-        node = self._refmap[mark]
-        return self._repo[node]
-
     def applychanges(self, repo, tr, changes):
         """Apply a list of changes to bookmarks
         """
@@ -271,7 +267,7 class bmstore(object):
                     return []
                 rev = self._repo[target].rev()
                 anc = self._repo.changelog.ancestors([rev])
-                bmctx = self.changectx(mark)
+                bmctx = self._repo[self[mark]]
                 divs = [self._refmap[b] for b in self._refmap
                         if b.split('@', 1)[0] == mark.split('@', 1)[0]]
 
@@ -412,11 +408,11 def update(repo, parents, node):
     bmchanges = []
     if marks[active] in parents:
         new = repo[node]
-        divs = [marks.changectx(b) for b in marks
+        divs = [repo[marks[b]] for b in marks
                 if b.split('@', 1)[0] == active.split('@', 1)[0]]
         anc = repo.changelog.ancestors([new.rev()])
         deletefrom = [b.node() for b in divs if b.rev() in anc or b == new]
-        if validdest(repo, marks.changectx(active), new):
+        if validdest(repo, repo[marks[active]], new):
             bmchanges.append((active, new.node()))
 
     for bm in divergent2delete(repo, deletefrom, active):

mercurial/discovery.py

@@ -301,7 +301,7 def _nowarnheads(pushop):
     for bm in localbookmarks:
         rnode = remotebookmarks.get(bm)
         if rnode and rnode in repo:
-            lctx, rctx = localbookmarks.changectx(bm), repo[rnode]
+            lctx, rctx = repo[localbookmarks[bm]], repo[rnode]
             if bookmarks.validdest(repo, rctx, lctx):
                 bookmarkedheads.add(lctx.node())
         else: