v0.2.1

Fixed

• A task that succeeded after its lease was lost no longer keeps the reaper's
  lost-lease record in errors. That record says the outcome was never
  observed, and the success write is that observation, so anything reading
  result.errors was handed an exception nobody raised on a task that worked.
  A failure resolving the same way already dropped it, and the two now agree. A task that is still LOST keeps the record: it is
  the only thing on the row that says why the result reads as failed.

Added

• tools/check_release.py --dist opens the built wheel and sdist and checks
  that each one carries every migration in the source tree, along with the
  licence and the package modules. A packaging rule that stops shipping a
  migration leaves a distribution that imports and passes its tests, and fails
  on somebody's upgrade against a column that is not there. The release
  workflow runs it after the build.