Description of problem:
Configuration is lost when updating hostgroup with hammer

When used "hammer hostgroup update" to change a certain value, some other configurations about the host is lost.  

For example:

A host group with following puppet settings:

# hammer hostgroup info --name rhel7-snp-client-lab | grep -A1 Puppet
Puppet CA Proxy Id:     2
Puppet Master Proxy Id: 2
ComputeProfile:
Puppetclasses:
    cis::el7all

If updated the Puppetclasses parameter, it will loose the information about puppet proxy:

# hammer hostgroup update --name rhel7-snp-client-lab --puppet-classes 'cis::el7all'
Hostgroup updated
# hammer hostgroup info --name rhel7-snp-client-lab | grep -A1 Puppet
Puppet CA Proxy Id:
Puppet Master Proxy Id:
ComputeProfile:
Puppetclasses:
    cis::el7all

And vise versa.

I would expect updating a single parameter shouldn't affect other parameters. Unless there is any dependences, which should be clearly documented.


Version-Release number of selected component (if applicable): Satellite 6.1

How reproducible: Always

Expected results:
Updating a single parameter shouldn't affect other parameters. Unless there is any dependences, which should be clearly documented.