I would have expected that sessions are completely independent from each other, and don't magically inherit some (but not others) environment variables from when the first session was created. (Especially considering the first session might not even exist anymore!)

That said, I can understand why it would work this way for simplicity, if all sessions are hosted inside the same process.

Luckily for me, I never use more than one session at a time, so this doesn't affect me.