rust-blackbox: use `is_extension_enabled` config helper
It's there, may as well use it to make the code clearer and less bug-prone.
# Copyright (C) 2006 - Marco Barisione <marco@barisione.org>
#
# This is a small extension for Mercurial (https://mercurial-scm.org/)
# that removes files not known to mercurial
#
# This program was inspired by the "cvspurge" script contained in CVS
# utilities (http://www.red-bean.com/cvsutils/).
#
# For help on the usage of "hg purge" use:
# hg help purge
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, see <http://www.gnu.org/licenses/>.
'''command to delete untracked files from the working directory (DEPRECATED)
The functionality of this extension has been included in core Mercurial since
version 5.7. Please use :hg:`purge ...` instead. :hg:`purge --confirm` is now
the default, unless the extension is enabled for backward compatibility.
'''
# This empty extension looks pointless, but core mercurial checks if it's loaded
# to implement the slightly different behavior documented above.
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'