ui: add a context manager for silencing the ui (pushbuffer+popbuffer)
We often silence the ui by calling `ui.pushbuffer()` followed (a later
in the code) by `ui.popbuffer()`. These places can be identified by
the fact that they ignore the output returned from
`ui.popbuffer()`. Let's create a context manager for these cases, to
avoid repetition, and to avoid accidentally leaving the ui silent on
exceptions. I deliberately called the new function `silent()` instead
of `buffered()`, because it's just an implementation detail that it
uses `pushbuffer()` and `popbuffer()`. We could later optimize it to
not buffer the output.
Differential Revision: https://phab.mercurial-scm.org/D10884
# __init__.py - Startup and module loading logic for Mercurial.
#
# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
# Allow 'from mercurial import demandimport' to keep working.
import hgdemandimport
demandimport = hgdemandimport