---
upgrade:
  - |
    The default merge mode used by Zuul for preparing git repos was
    previously :value:`project.merge-mode.merge-resolve` in all cases,
    but is now :value:`project.merge-mode.merge` for all drivers except
    Gerrit, where :value:`project.merge-mode.merge-resolve` is still
    the default.  This makes the merge operations performed by Zuul
    more closely match the operations that will be performed by the
    code review systems.