* core: Failed deployments no longer block migrations [[GH-4659](https://github.com/hashicorp/nomad/issues/4659)]
* client: Added option to prevent Nomad from removing containers when the task exits [[GH-4535](https://github.com/hashicorp/nomad/issues/4535)]
BUG FIXES:
* core: Reset queued allocation summary to zero when job stopped [[GH-4414](https://github.com/hashicorp/nomad/issues/4414)]
* core: Fix inverted logic bug where if `disable_update_check` was enabled, update checks would be performed [[GH-4570](https://github.com/hashicorp/nomad/issues/4570)]
* core: Fix panic due to missing synchronization in delayed evaluations heap [[GH-4632](https://github.com/hashicorp/nomad/issues/4632)]
* core: Fix treating valid PEM files as invalid [[GH-4613](https://github.com/hashicorp/nomad/issues/4613)]
* core: Fix panic in nomad job history when invoked with a job version that doesn't exist [[GH-4577](https://github.com/hashicorp/nomad/issues/4577)]
* core: Fix issue with not properly closing connection multiplexer when its context is cancelled [[GH-4573](https://github.com/hashicorp/nomad/issues/4573)]
* core: Upgrade vendored Vault client library to fix API incompatibility issue [[GH-4658](https://github.com/hashicorp/nomad/issues/4658)]
* driver/docker: Fix kill timeout not being respected when timeout is over five minutes [[GH-4599](https://github.com/hashicorp/nomad/issues/4599)]