firefox private browsing issue

[Eyal Lebedinsky]

I thought I should ask here before logging an issue with ff.

I discovered that when I do banking in firefox [54.0 (64-bit) on f24], after I log out
and open the login page again, I am not asked for the user/pwd but am allowed straight in.
After I log out I also clear cache/cookies but I am still allowed in.
If I log out a second time then it takes.

This does not happen in a standard window.

Has anyone noticed this? Or is it likely to be a problem with the bank?