graft: use context manager for config override Differential Revision: https://phab.mercurial-scm.org/D3738

tests: suppress read(-1) -> '' calls in fileobjectobserver This stabilizes the test output of the low-level wireproto tests between Python 2 and 3. I don't feel great about this change, but otherwise we get a ton of extra read(-1) output on Python 3, and this feels like a more sustainable solution. Bonus: test-ssh-proto-unbundle.t now passes on Python 3. Differential Revision: https://phab.mercurial-scm.org/D3733

debugcommands: work around logiofd being a pipe and unseekable This was breaking in our Python 3 build, but not Python 2. I don't know how it ever worked in Python 2, but this passes on both. Differential Revision: https://phab.mercurial-scm.org/D3732

py3: replace `unicode` with pycompat.unicode unicode() is not available on Python 3 and throws a NameError because unicodes are now default str() on py3. Differential Revision: https://phab.mercurial-scm.org/D3708

cmdutil: say that `graft --stop` stops the graft instead of aborting I am going to add a --abort flag to graft soon, so we make sure we differentiate between the what --stop flag does and what --abort does and don't use the words interchangeably. Differential Revision: https://phab.mercurial-scm.org/D3735

py3: two more passing tests from the ratchet in buildbot Differential Revision: https://phab.mercurial-scm.org/D3736

bdiff: one more safe call of bdiff_freehunks(NULL)

bdiff: document that bdiff_freehunks() accepts NULL blocks() of cext/bdiff.c may pass NULL on OOM.

hgweb: propagate http headers from ErrorResponse for web interface commands This makes it possible for e.g. authorization hooks to provide appropriate headers to make the web browser ask for credentials. It's done in the same way as the existing code in wireprotoserver.py.

py3: fix map() use in templatekw.showpredecessors() Now it matters since hybrid.tobool() no longer consumes the generator.