absorb: preserve branch-closing changesets even if empty
This makes the behavior consistent with 'hg commit', which allows to create
otherwise empty changesets if they close the branch. A lost branch closure can
inadvertently re-open a branch, so it should be preserved.
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.