largefiles: avoid dynamically subclassing context instances E.g. copies.pathcopies() compares context objects for equality and basectx.__eq__ compares the type. But since largefiles was dynamically creating classes, they would all be unequal. That led pathcopies(), after some changes I made, to not short-circuit to get copy info only from the dirstate. This patch fixes that short-circuiting (and other places where context are being compared for equality). Differential Revision: https://phab.mercurial-scm.org/D7143

relnotes: copy "next" to "5.2" and clear "next" This is the same thing as we did for 5.1 in cba59b338976 (relnotes: copy "next" to "5.1" and clear "next", 2019-08-01). Differential Revision: https://phab.mercurial-scm.org/D7231

py3: avoid `b'%s' % type(...)` in a ProgrammingError Differential Revision: https://phab.mercurial-scm.org/D7363

largefiles: delete unused repo.status_nolfiles() Differential Revision: https://phab.mercurial-scm.org/D7142

largefiles: use context manager for wlock in repo.status() override Differential Revision: https://phab.mercurial-scm.org/D7141

largefiles: allow "lfstatus" context manager to set value to False Differential Revision: https://phab.mercurial-scm.org/D7140

largefiles: move lfstatus context manager to lfutil Differential Revision: https://phab.mercurial-scm.org/D7139

revlog: delete references to deleted nullid sentinel value We stopped keeping the nullid in the index in 781b2720d2ac (index: don't include nullid in len(), 2018-07-20). I forgot to update some comments about it. Differential Revision: https://phab.mercurial-scm.org/D7366

revlog: remove the, now unused, `revlog._nodepos` attribute Spotted by Yuya Nishihara.

py3: fix sorting of obsolete markers in obsutil (issue6217) This is similar to 01e8eefd9434 and others. We move the sortedmarkers() function from exchange module to obsutil.

nodemap: use bytes for the error message Spotted by Yuya Nishihara.

py3: use native strings when forming email headers in patchbomb Per previous changesets, encoded header's values are native str. We complete the change in patchbomb extension to have literal header values native str as well. Then we can also change headers' keys to be str. In _msgid(), we still need to use encoding.strfromlocal() because usage of os.environ is not allowed by check-code. This finally removes the "if pycompat.ispy3:" TODO.