[8.x] Updated EmailVerificationRequest.php to check if user is not already verified

[ScriptingBeating]

This PR solves issue #35168 It adds the condition to check if the user's email is not already verified before updating it in the database and does not fire the Verified event

[GrahamCampbell]

This code will suffer from race conditions, so won't actually work in the way you expect.

[paras-malhotra]

I don't think there are any race conditions here. It's a simple check on the user object.

[GrahamCampbell]

The race condition is the user double opens the verify link. Both requests get a user that has not been verified yet. The event still fires twice. On those grounds, I don't think it makes sense to merge this PR, since it indicates the event will always fire exactly once, when it won't.

[ScriptingBeating]

since it indicates the event will always fire exactly once

Where it is indicated? The description just says that it adds a condition before updating the database and firing the event.

[GrahamCampbell]

Where it is indicated? The description just says that it adds a condition before updating the database and firing the event.

Yep, but the whole point of that is to "only fire the verification event once".