packaging: add docutils as dependency The previous commit revealed that attempting to run `python setup.py build_doc` from the packaging virtualenv failed due to missing docutils package. We didn't notice this before because py2exe Windows packaging appears to use a Python from another virtualenv (which does include docutils) to invoke setup.py. I discovered this as part of implementing packaging outside of that virtualenv environment. Differential Revision: https://phab.mercurial-scm.org/D8470

setup: use sysstr() on process output Otherwise we get a str-bytes mismatch on Python 3 if an error occurs. Differential Revision: https://phab.mercurial-scm.org/D8469

automation: install latest Python versions in Linux Staying up to date. Keeping parity with the Windows environment. Differential Revision: https://phab.mercurial-scm.org/D8467

contrib: update to latest Python 2.7, 3.7, and 3.8 We would ideally update the 3.5 and 3.6 versions as well. But Python didn't generate exe installers for newer versions for some reason. Differential Revision: https://phab.mercurial-scm.org/D8466

automation: always use latest Windows AMI The old AMI isn't available any more. We seem to run into this problem every few months. Amazon (or Microsoft) appears to be removing the old AMIs when they are superseded or something. Let's give up on tracking known images and switch the image selection logic to use the latest published image. Differential Revision: https://phab.mercurial-scm.org/D8465

rust-chg: reimplement attach_io operation as async function In short, MessageLoop<Connection> was redesigned as Protocol<Connection>, and the protocol methods no longer consume self. API changes are briefly documented in the following page: https://docs.rs/tokio-hglib/0.3.0/tokio_hglib/struct.Protocol.html Differential Revision: https://phab.mercurial-scm.org/D8442

rust-chg: upgrade to futures-0.3 based libraries And do some trivial fixes: - BytesMut::put_u32_be() -> put_u32() - tokio_process -> tokio::process, CommandExt -> Command, spawn_async() -> spawn(), stdin() -> stdin - tokio_timer::sleep() -> tokio::time::delay_for() Differential Revision: https://phab.mercurial-scm.org/D8441

rust-chg: exclude futures-dependent modules from build and break things It's impractical to upgrade the codebase incrementally since futures 0.1 and 0.3 APIs are fundamentally different. So this patch temporarily excludes futures-dependent modules from the build. These modules will be upgraded and re-enabled one by one. Differential Revision: https://phab.mercurial-scm.org/D8440

tests: stabilize test-log.t on Windows I think this is because Windows doesn't recognize single quote. Other ssh based clones use this clunky style too. Differential Revision: https://phab.mercurial-scm.org/D8459

tests: stabilize test-convert-hg-source.t on Windows This was a missing update in 1b8fd4af3318. Differential Revision: https://phab.mercurial-scm.org/D8458

commit: tell user what to do with .hg/last-message.txt I have always assumed that the message will be reused by the next `hg commit`, but it seems it's just silently dropped on the next commit. Let's try to be more helpful by telling the user that they have to manually tell hg to reuse it. The file will still be lost if the user runs some other operation in between (like a non-in-memory rebase). That will be fixed once we've switched all operations to be in-memory :) I didn't include `$(hg root)/` in the path in the message to the user because that would have made the message too long. Hopefully the user will figure that part out themselves. Differential Revision: https://phab.mercurial-scm.org/D8463

test-check-rust-format: specify --edition=2018 rustfmt doesn't read Cargo.toml unless it's executed by cargo. https://github.com/rust-lang/rustfmt#rusts-editions