contrib: stop whining about whitespace around = This was conflicting with black, so dump it. Differential Revision: https://phab.mercurial-scm.org/D6979

contrib: black manages whitespace after Python keywords now Differential Revision: https://phab.mercurial-scm.org/D6978

contrib: allow trailing commas in lists black manages this for us, so we don't need to worry about this anymore. Differential Revision: https://phab.mercurial-scm.org/D6977

contrib: remove check-code line length limit Both Python and C code are managed by formatters now, so relax this. Differential Revision: https://phab.mercurial-scm.org/D6976

changegroup: use positive logic for treemanifest changegroup3 logic We are about to add more cases, in that context, it is simpler to avoid double negative. En addition, We document the situation for the next soul. Differential Revision: https://phab.mercurial-scm.org/D6938

fix: add :enabled sub-config for fixer tools This allows distributing opt-in fixer tool configurations in .hgrc files. This may be useful for adding default configs in core, or for orgranizations that want to provide configs to their users. Tools are still enabled by default because it would be confusing to add a config and find that it has no effect until you add enabled=true. Differential Revision: https://phab.mercurial-scm.org/D6975

automation: add a command to submit to a Try server The CI code for running the Try Server requires more thorough review. Let's add just the client-side bits for submitting to Try so others can start using it. Differential Revision: https://phab.mercurial-scm.org/D6983