Spotted by Elitre and confirmed by me on translatewiki.net, verified by me on http://en.wikipedia.beta.wmflabs.org with a new account created on purpose:
- Register an account with password and email
- Confirm email
- Log out
- Visit Special:PasswordReset and enter username to get password by email
- Try to login with the received email
I) Expected: I'm logged in.
Incorrect password entered. Please try again.
(With any number of attempts.)
Last time something like this happened to me, on bug 56114, I was told it was some problem with wikitech's encryption package; there's also a similar report by another wiki on bug 52570.