The "bisect" command:

Usage: fossil bisect SUBCOMMAND ...

Run various subcommands useful for searching for bugs.

  fossil bisect bad ?VERSION?

    Identify version VERSION as non-working.  If VERSION is omitted,
    the current checkout is marked as non-working.

  fossil bisect good ?VERSION?

    Identify version VERSION as working.  If VERSION is omitted,
    the current checkout is marked as working.

  fossil bisect log
  fossil bisect chart

    Show a log of "good" and "bad" versions.  "bisect log" shows the
    events in the order that they were tested.  "bisect chart" shows
    them in order of check-in.

  fossil bisect next

    Update to the next version that is halfway between the working and
    non-working versions.

  fossil bisect options ?NAME? ?VALUE?

    List all bisect options, or the value of a single option, or set the
    value of a bisect option.

  fossil bisect reset

    Reinitialize a bisect session.  This cancels prior bisect history
    and allows a bisect session to start over from the beginning.

  fossil bisect vlist|ls|status ?-a|--all?

    List the versions in between "bad" and "good".

  fossil bisect ui

    Like "fossil ui" except start on a timeline that shows only the
    check-ins that are part of the current bisect.

  fossil bisect undo

    Undo the most recent "good" or "bad" command.

Summary:

  fossil bisect bad ?VERSION?
  fossil bisect good ?VERSION?
  fossil bisect log
  fossil bisect chart
  fossil bisect next
  fossil bisect options
  fossil bisect reset
  fossil bisect status
  fossil bisect ui
  fossil bisect undo