dirstate: drop unused condition in `from_p2` This conditional was added (by me) tentatively because "it seemed more correct", but it is not used anywhere yet, and it is missing from the C and the Rust implementation. So it seems more consistent to drop it for now. This effectively backout f94cc63df859c Differential Revision: https://phab.mercurial-scm.org/D11510

dirstate: drop all logic around the "non-normal" sets The dirstate has a lot of code to compute a set of all "non-normal" and "from_other_parent" entries. This is all used in one, unique, location, when `setparent` is called and moved from a merge to a non merge. At that time, any "merge related" information has to be dropped. This is mostly useful for command like `graft` or `shelve` that move to a single-parent state -before- the commit. Otherwise the commit will already have removed all traces of the merge information in the dirstate (e.g. for a regular merges). The bookkeeping for these sets is quite invasive. And it seems simpler to just drop it and do the full computation in the single location where we actually use it (since we have to do the computation at least once anyway). This simplify the code a lot, and clarify why this kind of computation is needed. The possible drawback compared to the previous code are: - if the operation happens in a loop, we will end up doing it multiple time, - the C code to detect entry of interest have been dropped, for now. It will be re-introduced later, with a processing code directly in C for even faster operation. Differential Revision: https://phab.mercurial-scm.org/D11507

dirstate: use a new `drop_merge_data` in `setparent` What is happening in this `setparent` loop is that we remove all `merge` related information when the dirstate is moved out of a `merge` situation. So instead of shuffling state to get them where we want, we simply add a method on the DirstateItem to do drop the information we want dropped. Differential Revision: https://phab.mercurial-scm.org/D11506