dirstate: move opendirstatefile to dirstatemap
As part of moving the dirstate storage logic to another class, let's move
opendirstatefile to dirstatemap. This will allow extensions to replace the
pending abstraction.
Future patches will move the consumers of _opendirstatefile into dirstatemap as
well.
Differential Revision: https://phab.mercurial-scm.org/D757
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.