histedit: use hg.updaterepo() to avoid ui.{push|pop}buffer() hack

In some parts of code, we call hg.update() and surround that with
ui.pushbuffer() and ui.popbuffer() to suppress the output returned by
hg.update().

We have hg.updaterepo() which does not writes to UI and can be used instead.

Differential Revision: https://phab.mercurial-scm.org/D3862

hgext/histedit.py

@@ -779,9 +779,7 b' class fold(histeditaction):'
 
     def finishfold(self, ui, repo, ctx, oldctx, newnode, internalchanges):
         parent = ctx.parents()[0].node()
-        repo.ui.pushbuffer()
-        hg.update(repo, parent)
-        repo.ui.popbuffer()
+        hg.updaterepo(repo, parent, False)
         ### prepare new commit data
         commitopts = {}
         commitopts['user'] = ctx.user()
@@ -812,9 +810,7 b' class fold(histeditaction):'
                          skipprompt=self.skipprompt())
         if n is None:
             return ctx, []
-        repo.ui.pushbuffer()
-        hg.update(repo, n)
-        repo.ui.popbuffer()
+        hg.updaterepo(repo, n, False)
         replacements = [(oldctx.node(), (newnode,)),
                         (ctx.node(), (n,)),
                         (newnode, (n,)),
@@ -1176,9 +1172,7 b' def _continuehistedit(ui, repo, state):'
 
 def _finishhistedit(ui, repo, state, fm):
     """This action runs when histedit is finishing its session"""
-    repo.ui.pushbuffer()
-    hg.update(repo, state.parentctxnode, quietempty=True)
-    repo.ui.popbuffer()
+    hg.updaterepo(repo, state.parentctxnode, False)
 
     mapping, tmpnodes, created, ntm = processreplacement(state)
     if mapping: