Description of problem:

A satellite 6.16.1 can perform host builds just fine. But when we create a shell hook and subscribe it to the "Build Entered" event, that does not allow creating and submitting a host for the build will result in a "Name has already been taken" error but the host entry would be created ( perhaps partially ). 

How reproducible:

100%

Is this issue a regression from an earlier version:

Yes ( it works fine on 6.15.z and before )

Steps to Reproduce:

1. Install a satellite 6.16.1 and configure it for system build ( DHCP \ DNS \ TFTP \ kickstart \ HG \ CV \ LCE \ Subnet \ Domain \ Activation Key )

2. Try to submit a fake system build using a fake mac address and see if the build submission works as expected or not. 

3. Enable shellhook feature via installer

4. Setup a basic shellhook script, template and webhook and subscribe it to Build Entered event. 

5. Repeat step 2 with a different name , mac and IP while monitoring proxy.log and production.log 

6. Simply disable the Webhook and repeated Step 5 with a new IP and mac and name.

Actual behavior:

• Host entry created in backend but it also shows "Failed to save: Name has already been taken"
• I get to see "ForemanWebhooks::EventSubscriber: build_entered.event.foreman event received" but nothing else after that in production.log or proxy.log
• If i click on Cancel on the form, Then i get to see the host entry is created but perhaps partially. 
• Step 6 would be successful. 

Expected behavior:
Everything should work as it did on Satellite 6.15 or before. 

Business Impact / Additional info:

Unable to build hosts.

Unable to use shellhooks or webhooks for further automation.