providers_docker.yml in vagrant-unbundled-2.2.7.0

- old
+ new

@@ -157,9 +157,11 @@
         with `vagrant up`. If the container always goes to "stopped"
         right away after being started, it is because the command being
         run exits and doesn't keep running.
 
     errors:
+      build_error: |-
+        Vagrant received unknown output from `docker build` while building a container: %{result}
       compose_lock_timeout: |-
         Vagrant encountered a timeout waiting for the docker compose driver
         to become available. Please try to run your command again. If you
         continue to experience this error it may be resolved by disabling
         parallel execution.