dirstate-entry: add a `merged` property Lets start to define and use more semantic property. Differential Revision: https://phab.mercurial-scm.org/D10955

dirstate-entry: add a `state` property (and use it) This replace the [0] access. Ultimately is we should probably get ride of this in its current form. However this is a good transitional solution to move away for tuple indexing for now. Differential Revision: https://phab.mercurial-scm.org/D10954

dirstate: move most of the `remove` logic with dirstatemap `removefile` This code deal with special logic to preserving "merged" and "from_p2" information when removing a file. These are implementation details that are more suitable for the dirstatemap layer. Since the dirstatemap layer alreaday have most of the information necessary to do so, the move is easy. This move helps us to encapsulate more implementation details within the dirstatemap and its entry. Easing the use of a different storage for dirstate v2. Differential Revision: https://phab.mercurial-scm.org/D10953

dirstate: add a `in_merge` property This factor the "p2 is not null" check and is fairly simpler to read. Differential Revision: https://phab.mercurial-scm.org/D10952

dirstate-entry: introduce dedicated accessors for v1 serialization In the spirit of changing the content and storage of the dirstate entry, we add new method that the code doing v1 serialisation can use. Adding such method to the C object is quite trivial. Differential Revision: https://phab.mercurial-scm.org/D10951

dirstate-entry: goes through the `dirstatetuple` constructor in all cases We need to make sure we build an object. Differential Revision: https://phab.mercurial-scm.org/D10950

dirstate-entry: turn dirstate tuple into a real object (like in C) With dirstate V2, the stored information and actual format will change. This mean we need to start an a better abstraction for a dirstate entry that a tuple directly accessed. By chance, the C code is already doing this and pretend to be a tuple. So it should be fairly easy. We start with turning the tuple into an object, we will slowly migrate the dirstate code to no longer use the tuple directly in later changesets. Differential Revision: https://phab.mercurial-scm.org/D10949

dirstate: split dirstatemap in its own file The dirstate file is large enough and the dirstatemap is quite insulated logic already. Differential Revision: https://phab.mercurial-scm.org/D10934

run-tests: stop writing a `python3` symlink pointing to python2 Having `python3` actually pointing to `python2` is bad. So we stop doing so. In addition we need to re-introduce a `python` executable since some of the script really need to be able to say "current python" in their shbang. For example, `hghave` is one of such script. The faulty changes where introduced by c102b704edb5. Differential Revision: https://phab.mercurial-scm.org/D10943

check-code: stop forbidding return code result There is no explication of what is the intend of that check and what is the alternative. I suspect this comes from the transition to the "unified test" format circa 2010. With the non zero return explicitly listed in the output explicit $? checking became Redundant. However there is valid use case for checking $? so I am dropping this check. Differential Revision: https://phab.mercurial-scm.org/D10994