cmdutil: pass metadata from amend() to cleanupnodes

`commit --amend` and amend command in core and extensions rely on
cmdutil.amend() for amending a commit. So the logic to add a note to amend must
reside here. This patch assumes that note will be passed in opts dictionary to
the function and it will be passed to cleanupnodes and then createmarkers to
store the note in the obsmarker metadata.

After this patch, note can be stored on an amend changeset by passing notes as a
part of opts to cmdutil.amend().

Differential Revision: https://phab.mercurial-scm.org/D1094

mercurial/cmdutil.py

@@ -3152,7 +3152,10 b' def amend(ui, repo, old, extra, pats, op'
         # Reroute the working copy parent to the new changeset
         repo.setparents(newid, nullid)
         mapping = {old.node(): (newid,)}
-        scmutil.cleanupnodes(repo, mapping, 'amend')
+        obsmetadata = None
+        if opts.get('note'):
+            obsmetadata = {'note': opts['note']}
+        scmutil.cleanupnodes(repo, mapping, 'amend', metadata=obsmetadata)
 
         # Fixing the dirstate because localrepo.commitctx does not update
         # it. This is rather convenient because we did not need to update