histedit: move finishfold into fold class

Let's move the finishfold function into the fold class so we can modify it from
the roll class more easily.

hgext/histedit.py

@@ -546,13 +546,10 class fold(histeditaction):
         if isinstance(self, rollup):
             foldopts['rollup'] = True
 
-        return finishfold(repo.ui, repo, parentctx, rulectx, ctx.node(),
+        return self.finishfold(repo.ui, repo, parentctx, rulectx, ctx.node(),
                           foldopts, middlecommits)
 
-class rollup(fold):
-    pass
-
-def finishfold(ui, repo, ctx, oldctx, newnode, opts, internalchanges):
+    def finishfold(self, ui, repo, ctx, oldctx, newnode, opts, internalchanges):
     parent = ctx.parents()[0].node()
     hg.update(repo, parent)
     ### prepare new commit data
@@ -571,8 +568,8 def finishfold(ui, repo, ctx, oldctx, ne
     commitopts['date'] = max(ctx.date(), oldctx.date())
     extra = ctx.extra().copy()
     # histedit_source
-    # note: ctx is likely a temporary commit but that the best we can do here
-    #       This is sufficient to solve issue3681 anyway
+        # note: ctx is likely a temporary commit but that the best we can do
+        #       here. This is sufficient to solve issue3681 anyway.
     extra['histedit_source'] = '%s,%s' % (ctx.hex(), oldctx.hex())
     commitopts['extra'] = extra
     phasebackup = repo.ui.backupconfig('phases', 'new-commit')
@@ -593,6 +590,9 def finishfold(ui, repo, ctx, oldctx, ne
         replacements.append((ich, (n,)))
     return repo[n], replacements
 
+class rollup(fold):
+    pass
+
 class drop(histeditaction):
     def run(self):
         parentctx = self.repo[self.state.parentctxnode]