Taxonomy terms are not deleted when you delete an user and it's content

Problem/Motivation

The issue was discovered while I was implementing a package of Behat tests for a website.
Initially I discovered that when you delete an user with the option - Delete the account and its content. - only his nodes are deleted but not the taxonomy terms he/she created.
As we try to keep the state of the website before and after the tests the same I delete each piece of content at the end of the test run. Currently I should create one test which deletes nodes and another that should chase taxonomy terms.

Steps to reproduce

1. Create a new user with the website
2. Create some content with it - both nodes and taxonomy terms
3. Delete the user with the option - Delete the account and its content.
4. Check if the content is deleted.

Current behaviour is as follows - nodes are deleted but terms stay.
What we aim after the bug fix - nodes and terms are deleted.

Proposed resolution

Probably we should have an author field attached to each term

Remaining tasks

• Validate this as a real bug
• Write a patch
• Reviews

User interface changes

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API changes

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Data model changes

I guess that if we follow proposed solution we should introduce changes in the database as well