Fixes#5856
When the scheduler looks for a placement for an allocation that's
replacing another allocation, it's supposed to penalize the previous
node if the allocation had been rescheduled or failed. But we're
currently always penalizing the node, which leads to unnecessary
migrations on job update.
This commit leaves in place the existing behavior where if the
previous alloc was itself rescheduled, its previous nodes are also
penalized. This is conservative but the right behavior especially on
larger clusters where a group of hosts might be having correlated
trouble (like an AZ failure).
Co-Authored-By: Michael Schurter <mschurter@hashicorp.com>
3716a67b30