AO3-6359 Fix Possible to delete the pseud that corresponds with your username if the capitalization or diacritics differ

[Dobe-Time]

AO3-6359 Fix Possible to delete the pseud that corresponds with your username if the capitalization or diacritics differ

Pull Request Checklist

• Have you read "How to write the perfect pull request"?
• Have you read the contributing guidelines?
• Have you added tests for any changed functionality?
• Have you added the Jira issue number
  as the first thing in your pull request title (e.g. AO3-1234 Fix thing)
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Issue

https://otwarchive.atlassian.net/browse/AO3-6359

Purpose

What does this PR do?
Fixes issue AO3-6359 where it was possible to delete the pseud that corresponds to your username if you already had a pseud with the same spelling but different capitalization or diacritics, the fix was to add a new path to the psued update function for when a username is updated. This new path checks if the user already has a matching pseud and updates the capitalization and diacritics to match the new username.

Testing Instructions

How can the Archive's QA team verify that this is working as you intended?
Similar to replication instructions from the ticket except for step number 4 where delete is now not possible.

1. Log in
2. Create a pseud
   a. Hi, username! > My Preferences > Manage My Pseuds > New Pseud
   b. Fill in the “Name” field with a something that will also be valid as a username (and is not currently someone’s username), e.g. Issue6359Test
   • Usernames must consist of 3 to 40 characters (A-Z, a-z, _, 0-9 only), no spaces, and cannot begin or end with underscore ( _ )
     c. Press "Create Pseud"
3. Change your username to a differently capitalized version of your new pseud
   a. Hi, username! > My Preferences > Change Username
   b. Fill in the “New user name” field with a differently capitalized version of your new pseud, e.g. issue6359test
   c. Fill in the “Password” field with your account password
   d. Press “Change Username”
4. Attempt to delete the pseud from Step 2 (This is no longer possible)
   a. Hi, username! > My Preferences > Manage My Pseuds
   b. There should not be an option to delete the pseud

If you have a Jira account with access, please update or comment on the issue
with any new or missing testing instructions instead.

You can remove this section if there are already full testing instructions in the Jira issue.

References

Are there other relevant issues/pull requests/mailing list discussions? If not, you can remove this section.

Yes: Old closed pull request for the same issue: #4307 (Closed for being years old)
Thank you Sarken, Brianjaustin, and Tickinginstant for your comments on the above PR, I have attempted to address them all in this new PR.

Credit

Credit

Dobe He/Him
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[sarken]

I just wanted to say a quick thank you for picking this back up!