Fix protoype object updates changing cached prototype

[chiizujin]

Brief overview of PR changes/additions

Fixes behaviour in #3505.

This was caused by the spawned object being used as a comparison for the update directly updating the dict in the prototype cache if it found one, rather than copy of it. This resulted in the cached prototype being changed to reflect the spawned object.

Motivation for adding to Evennia

Bug fix.

Other info

Note that this does not change the repeated save request behaviour mentioned in the bug report.

Before

Starting with an object spawned from a prototype and then adding a new tag ('tag_on_object') directly to the object:

>tag test
Tags on test: 'tag_on_object', 'test' (category: from_prototype)

Add a new tag to the prototype:

Actions: examine <num> | remove <num>
Back (attrs) | Forward (locks) | Index | Validate prototype | Quit

 1: new_tag          

Save and update spawned objects, then say "no" at the second save prompt:

Do you want to save/overwrite the existing prototype 'test'?
(...)
>n

View tags on prototype, without exiting the wizard:

Actions: examine <num> | remove <num>
Back (attrs) | Forward (locks) | Index | Validate prototype | Quit

 1: new_tag          

Reload the prototype while still in the wizard. The prototype in the wizard now has the tags that the spawned object had before it was updated:

Actions: examine <num> | remove <num>
Back (attrs) | Forward (locks) | Index | Validate prototype | Quit

 1: tag_on_object      
 2: test               

Note that the database has the correct tags. so quitting the wizard restarting the server and reloading the template will result in the correct tags.

The spawned object has the new tag:

>tag test
Tags on test: 'new_tag', 'tag_on_object', 'test' (category: from_prototype)

After

Starting from the same point as the start of the "before" test:

>tag test
Tags on test: 'tag_on_object', 'test' (category: from_prototype)

Go through the same steps to add a new tag, save, update, and say "no" at the second save prompt. Look at the tags on the prototype, without leaving the wizard:

Actions: examine <num> | remove <num>
Back (attrs) | Forward (locks) | Index | Validate prototype | Quit

 1: new_tag     

Reload the prototype while staying in the wizard and check the tags:

Actions: examine <num> | remove <num>
Back (attrs) | Forward (locks) | Index | Validate prototype | Quit

 1: new_tag          

The object has the new tag:

tag test
Tags on test: 'new_tag', 'tag_on_object', 'test' (category: from_prototype)

[Griatch]

Nice investigation and good job finding the fix!