Steps to reproduce:

1. Create host with discovery rule. 
2. Discovery rule should have correct key (we need discovered host).
3. Add host prototype with SNMPv3.
4. Fill context name with value - i_am_context
5. wait till host is discovered and created. 
6. Update host prototype, changed context name to - now_changed_context.
7. Check audit.

Result:

host.interfaces[16].details.contextname: now_changed_context => now_changed_context
Expected:
host.interfaces[16].details.contextname: i_am_context => now_changed_context