Unable to create new account after deleting one with same email

[MonoScyron]

Registered an account under an email address, then deleted it to change the username. Attempting to register a new account with the same email and different username sent a verification link that resulted in a "Register failed" message. Attempting to sign-in using GitHub results in this page being displayed:

Clicking the sign-in button directs to the same page.

Additional context:

• The first account was created with a different username, but all accounts afterward have the same username
• All accounts were created with the same email

[vednoc]

Try again, it should work now. Also, please don't close this issue because I want to fix soft deletion once and for all.

[MonoScyron]

Just tried to register with the same username and email as when I encountered the bug. The verification link was sent but I was still given a "Register failed" message.

[vednoc]

Interestingly enough, I can see that there's a new account with the same username as on GitHub. Could you try to sign in?

[MonoScyron]

Just tried and it logged in fine. Not sure what happened with the verification email, but it looks like the account creation worked 👍

[vednoc]

I can see that our database got locked for five seconds, as well as three other attempts within a minute, so that could be why. Not entirely sure why it happened, but we do hash passwords during that process and it usually takes a bit of time for bcrypt to complete. The traffic doesn't look unusual either. This situation is where it would've been really handy if we had tracing.