rhg: Add a `rhg.on-unsupported` configuration key For now the two values are: * `abort-silent`: silently exit with code 252, the previous default behavior * `abort`: print an error message about what feature is not supported, then exit with code 252. Now the default. Differential Revision: https://phab.mercurial-scm.org/D10091

rhg: Make configuration available as early as possible in main() Differential Revision: https://phab.mercurial-scm.org/D10090

rust: Upgrade Cargo.lock to the newer format As discussed in https://phab.mercurial-scm.org/D10085#153099 See https://github.com/rust-lang/cargo/pull/7070 and https://blog.rust-lang.org/2020/01/30/Rust-1.41.0.html#less-conflict-prone-cargolock-format Differential Revision: https://phab.mercurial-scm.org/D10089

sshpeer: enable+fix warning about sshpeers not being closed explicitly I recommend looking at this with a diff that ignores indentation. The test changes are because localrepo.close() updates some cache, which appears happens earlier now on rollbacks or strips or something. The http changes are because httppeer.close() prints stats with --verbose. Differential Revision: https://phab.mercurial-scm.org/D9999

sshpeer: add a develwarning if an sshpeer is not closed explicitly The warning is disabled until the next commit, because fixing it results in a noisy diff due to indentation changes. Differential Revision: https://phab.mercurial-scm.org/D9998

remotefilelog: rework workaround for sshpeer deadlocks The wrapping of `sshpeer.cleanup` silently broke when `cleanup` was renamed to `_cleanup`, a couple of years ago. I don't know what `orig.im_self` is, but regardless, the intention of the wrapping seems pretty clear: close stderr before sshpeer._cleanuppipes blocks on it. So do that. Differential Revision: https://phab.mercurial-scm.org/D9997

sshpeer: add a method to check if a doublepipe is closed So we can tell in a next commit if we're trying to close an already closed connection or not (in which case, we may warn). Differential Revision: https://phab.mercurial-scm.org/D9996

sshpeer: make sshpeer.close() close the underlying connection So the connection can be closed eagerly in future commits, instead of relying on __del__. Differential Revision: https://phab.mercurial-scm.org/D9995