Users are logged-in when using credentials of an not yet active account

Causing this issue :

I am facing a problem with user registration. An user registers by putting
all the required fields and he gets a page saying that 'Registration is
successfull'. A validation email is also been send to him. If he tries to
login without activation, XWiki logs him in and gives a message 'Your
account is not yet active, because your email has not yet been confirmed.'.
He goes back to his mail box, copies the activation link and paste it on the
same window. But the page remains the same and doesn't allow the user to
activate his account. He need to open a new browser or logout to activate
his account and login to XWiki. This looks like a bug. Any comments on this
? I am using XE 1.6.