phases: rename variable used for owned dict of phasesets The phaseroots variable is used for two different objects: borrowed set and owned dict of sets. It's hard to track which object should have to be decrefed on error return.

phases: leverage Py_BuildValue() to build PyInt and steal PyObject "N" means "O" without incref, so we can just return the created tuple.

phases: make sure an exception should be set on error return This should never happen, but the code looks wrong without PyErr_Set*() call.

phases: fix clang-format error

phases: fix error return with no exception from computephases() PySet_Check() does not set an exception.

osutil: fix excessive decref on tuple creation failure in listdir() The stat object would be freed on error for the same reason as the previous patch. makestat() can be inlined, but this patch doesn't change it. https://github.com/python/cpython/blob/2.7/Python/modsupport.c#L292 The __APPLE__ code is untested.

revlog: fix excessive decref on tuple creation failure in parse_index2() Since Py_BuildValue() steals the ownership of "N" arguments, these objects would already be freed if Py_BuildValue() returned NULL. https://github.com/python/cpython/blob/2.7/Python/modsupport.c#L292

tests: correctly match clang-format version >= 10 The previous regex only matched the first digit, so "clang-format version 10.0.0" was recognized as version 1.

state: support validated declaration of nested unfinished ops This enables extensions to define commands that delgate to rebase, evolve, etc. one or more times to also have their own unfinished states for the full sequence of operations without monkey-patching _unfinishedstates. Differential Revision: https://phab.mercurial-scm.org/D8714

absorb: improve message for the case when changeset became empty In changeset f55099982bc5, I introduced the message "became empty and became ...", which I was never very happy with. Raphaël Gomès suggested "became empty as ...". That sounds much nicer. Differential Revision: https://phab.mercurial-scm.org/D8765