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

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

--- a/hgext/infinitepush/bundleparts.py	Wed Sep 25 13:50:48 2019 -0400
+++ b/hgext/infinitepush/bundleparts.py	Wed Sep 25 17:57:16 2019 -0400
@@ -12,6 +12,7 @@
     changegroup,
     error,
     extensions,
+    node as nodemod,
     revsetlang,
     util,
 )
@@ -48,7 +49,7 @@
         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()`

--- a/mercurial/bookmarks.py	Wed Sep 25 13:50:48 2019 -0400
+++ b/mercurial/bookmarks.py	Wed Sep 25 17:57:16 2019 -0400
@@ -177,10 +177,6 @@
         """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 @@
                     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 @@
     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):

--- a/mercurial/discovery.py	Wed Sep 25 13:50:48 2019 -0400
+++ b/mercurial/discovery.py	Wed Sep 25 17:57:16 2019 -0400
@@ -301,7 +301,7 @@
     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: