read-passwd breaks tramp

[Liang Wang]

Hi,

In latest trunk, read-passwd change in revision 107874 breaks tramp.
When I try to C-x C-f /sudo::/etc/fstab RET, I can see

    Tramp: Opening connection for address@hidden using sudo...done

in echo area.  But I haven't had a chance to input password yet.  In
*Messages* buffer, I can see a line of message like:

    completion--some: Command attempted to use minibuffer while in minibuffer

By using previous version of read-passwd, I can use tramp without problems.

Thanks,
Liang.