mq: refactor patchheader header ordering to match export (BC) The refactoring also gives more robust and extendable handling of other HG headers.

mq: upgrade non-plain patches to HG format when setting parent in patchheader Parent will now always be updated or added when qrefreshing HG patches. Plain patches will not be changed, but patches that neither are plain nor HG will be upgraded to HG patches on first refresh.

mq: make patchheader .plainmode more reliable Instead of having to make extra checks whenever we use .plainmode, let the initial value consider the actual patch header content.

bundle2: remove heads and common arguments to getbundle parts generators

bundle2: separate bundle10 and bundle2 cases in getbundle() The primary goal is to make it easier for extensions to alter how bundle2 parts are laid out. They now can use the getbundle2partsgenerator decorator to add new parts, or directly act on getbundle2partsmapping to wrap existing part functions. Note the 'request for bundle10 must include changegroup' error was kept under the same conditions as before, although the logic changes don't make it obvious.

bundle2: pass b2caps down to functions adding bundle2 parts for getbundle

parsers: fix uninitialize variable warning The heads pointer is not initialized correctly if filter is false, causing both clang and gcc to issue a warning. Correctly initialize heads to NULL.

revset: use `subset &` in bare `p2()` This takes advantage of the `fullreposet` smartness with a nice speedup. It's a similar speedup to `p1()` when a merge is in progress (the non merge case is already lightning fast anyway.)

revset: use `subset &` in bare `p1()` This takes advantage of the `fullreposet` smartness and yields a nice speedup. revset #0: p1() 0) wall 0.003256 comb 0.010000 user 0.010000 sys 0.000000 (best of 527) 1) wall 0.000066 comb 0.000000 user 0.000000 sys 0.000000 (best of 23224)

revset: use `subset &` in `rev` This takes advantage of the `fullreposet` smartness and yields a nice speedup. revset #0: rev(25) 0) wall 0.005480 comb 0.000000 user 0.000000 sys 0.000000 (best of 305) 1) wall 0.000052 comb 0.000000 user 0.000000 sys 0.000000 (best of 21891)