hghave: disable demandimport when chg is running
Chg disables demandimport on purpose for performance wins and
therefore, it probably makes sense to indicate that demandimport is disabled
when chg is running.
Test Plan:
Ran all the tests.
Differential Revision: https://phab.mercurial-scm.org/D1161
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.