Email addresses and getting the wrong account when you sign in

I've just deployed a change to fix a very old bug, but in doing so some people will now see a side effect of the bug.

Background:

• We create your account, and your email address identifies it
  
• Whenever you sign in with that email, we give you your account
  
  

The bug was that we created duplicate accounts if:

• You sign-in with @gmail.com and originally used @googlemail.com
  
• You sign-in with user@ but originally used user+comment@
  
• You sign-in with u.s.e.r@ but originally used user@
  
  

In essence... if your email address even slightly varied from what you originally signed in with, we went and created a second account for you.

To solve this, I've created the idea of a canonical email address.

The fix is that no matter how I enter my email, I now understand that it is one and the same email:

• david.kitchen@gmail.com
  
• davidkitchen@gmail.com
  
• david.kitchen@googlemail.com
  
• david.kitchen+lfgss@gmail.com
  
• D.a.V.i.D.k.I.T.c.H.e.N+lfgss(comment)@googlemail.com
  
  

All of those are actually the same email (one I stopped using years ago, but meh).

This solves the bug, we no longer create duplicate accounts.

But...

If we had already created duplicate accounts, then during sign-in I'm going to give you the older account. The first one we saw.

That means for a tiny minority (around 0.5% of users), that we may now give you the wrong account. We fixed the big bug, but created an annoyance.

If this affects you... if now you get the wrong account when signing in. LET ME KNOW.

For those who let me know there is an issue, I'll let you know which profiles are affected and you can pick the one you want... and I'll nobble the other.