upgrade: add support to downgrade share safe mode
In previous patch we added support to upgrade current repository to use share
safe mode. This patch adds support to downgrade to remove share-safe mode.
Differential Revision: https://phab.mercurial-scm.org/D9358
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.