abort: added logic for of hg abort This is part of `GSoC19` project `Implement abort and continue commands`. This patch is part of the `abort plan`. This adds the basic logic for `hg abort`. This command aborts an multistep operation like graft, histedit, rebase, merge and unshelve if they are in an unfinished state. The first part of the logic is determining the unfinished operation from the state detection API under `statemod`. This API is extended to support `hg abort` by adding a method to register the abort logic as a function (here `abortfunc`). Once the unfinished operation is determined the registered logic is used to abort the command. The benefit of this kind of framework is that any new extension developed can support `hg abort` by registering the command and logic under statedetection API. `hg abort` currently supports `--dry-run/-n` flag only. It is used to dry run `hg abort` Further patches sequentially add support for `graft`, `rebase`, `unshelve`, `histedit` and `merge`. Differential Revision: https://phab.mercurial-scm.org/D6566

merge with stable

merge: disallow merge abort in case of an unfinished operation (issue6160) This patch disallows `hg merge --abort` in case an operation of higher precedence i.e unshelve, rebase, histedit are in unfinished states. This is done so as to avoid partial abort of these operations in case merge abort is called at an interrupted step. The patch adds a `cmdutil.getunfinishedstate` function which checks for operations under progress and returns a `statecheck` object for it. Differential Revision: https://phab.mercurial-scm.org/D6607

relnotes: document new range-select mechanism in crecord Differential Revision: https://phab.mercurial-scm.org/D6622

statecheck: updated docstrings related to afterresolvedstates Differential Revision: https://phab.mercurial-scm.org/D6606

extdata: avoid crashing inside subprocess when we get a revset parse error Differential Revision: https://phab.mercurial-scm.org/D6616

extdata: demonstrate bad behavior when a subprocess emits garbage Differential Revision: https://phab.mercurial-scm.org/D6615

py3: don't run source transformer on hgext3rd (extensions) It's unclear why the source transformer runs on hgext3rd. It's been like that since it was introduced in 1c22400db72d (mercurial: implement a source transforming module loader on Python 3, 2016-07-04), and that commit didn't say anything about it (but it says that it doesn't have "support [...] for extensions"). I find that the current handling of hgext3rd just makes it harder to convert extensions to Python 3. It makes you convert a bunch of strings passed to getattr() and kwargs[] to r'' that could otherwise have been left alone. It's also really confusing that the source transformer runs when you import the extension as "extensions.foo=", but not as "extension.foo=/some/path". I suppose there is small number of (very simple) extensions that would have worked without this patch that would now be broken. It seems okay to me to break those. Differential Revision: https://phab.mercurial-scm.org/D6614

crecord: provide 'X' as a range-select mechanism Differential Revision: https://phab.mercurial-scm.org/D6621

crecord: make KEY_ENTER usable in tests (by not updating UI) Differential Revision: https://phab.mercurial-scm.org/D6620