Modern / classic mode in arcanist


I have just updated arcanist to c471983697b3ad8260d32886bfd52fdc1a2486be (after several months without doing it), and now when I execute arc unit or arc lint they work, but show this message:

arc unit
 (::)  Workflow is unrecognized by modern "arc", falling through to classic mode.

Where can I find information about that “modern” or “classic” arc, so I can update the config files?

Here is my .arcconfig, if you need to see it:

    "phabricator.uri" : "",
    "repository.callsign": "XXX",
    "unit.engine": "PhpunitTestEngine",
    "unit.phpunit.binary": "vendor/bin/phpunit",
    "phpunit_config": "config/build/phpunit.xml.dist"

This is expected. No “modern” version of the unit workflow is available yet. See for some discussion.

You can use stable instead of master if you’d prefer not to see this message.

I’ll take a look at T13488, and consider changing to stable if somethings goes wrong. Thank you!