remove-hard-time-limit-vf2-be83830ecc71f72c.yaml

---
upgrade:
  - |
    The preset pass managers generated by :func:`~.level_1_pass_manager`,
    :func:`~.level_2_pass_manager`, and :func:`~.level_3_pass_manager` and used
    by the :func:`~.transpile` function's ``optimization_level`` argument at
    1, 2, and 3 respectively no longer set a hard time limit on the
    :class:`~.VF2Layout` transpiler pass. This means that the pass will no
    longer stop trying to find a better alternative perfect layout up until a
    fixed time limit (100ms for level 1, 10 sec for level 2, and 60 sec for
    level 3) as doing this limited the reproducibility of compilation when a
    perfect layout was available. This means that the output when using the pass
    might be different than before, although in all cases it would only change
    if a lower noise set of qubits can be found over the previous output. If
    you wish to retain the previous behavior you can create a custom
    :class:`~.PassManager` that sets the ``time_limit`` argument on the
    constructor for the :class:`~VF2Layout` pass.
fixes:
  - |
    Fixed an issue with reproducibility of the :func:`~.transpile` function
    when running with ``optimization_level`` 1, 2, and 3. Previously, under
    some conditions when there were multiple perfect layouts (a layout that
    doesn't require any SWAP gates) available the selected layout and output
    circuit could vary regardless of whether the ``seed_transpiler`` argument
    was set.