Description of problem:

1. Job execution fails (for any reason)
2. User wants to rerun job on failed hosts using hammer. 
3. Rerun job cannot be posted due to error below:

~~~
# hammer job-invocation rerun --id 20057 --failed-only=true
Validation failed: Targeting: Hosts is invalid
~~~

If "rerun failed" is called using webUI it works fine.

Version-Release number of selected component (if applicable):

Satellite 6.7 (customer) and Satellite 6.8 (internal reproducer)

How reproducible:

** Host on Satellite must have some inconsistent configurations (easy way to reproduce it is assigning a medium_id to the host that is not linked to its operating system) **

1. Try running a job and force it to fail (type wrong password, for example). Note the job id from the URL (https://192.168.250.100/job_invocations/20060 => job id is 20060)
2. Ensure host has a wrong medium_id assigned:

   - Create a random media on Satellite and get its id (let's say, medium_id = 12). Do not assign this media to the operating system of the host!
   - Assign the medium_id to the host manually:
~~~
echo "update hosts set medium_id = '12'  where id = '57';"|su - postgres -c "psql foreman"
~~~

3. Rerun the job using hammer and it will fail:

~~~
hammer job-invocation rerun --id 20060 --failed-only=true
~~~

On the webUI (https://192.168.250.100/job_invocations/20060) click option "Rerun failed" and job will start properly.

Actual results:

WebUI is able to rerun job. Hammer cannot rerun job due to extra verification.

Expected results:

WebUI and hammer should be able to rerun the job (or both should fail). I only expect consistency.

Additional info: