plymouth ask-for-password x2 always shows the prompt from the first call

This bug was fixed in the package plymouth - 0.8.1-1

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plymouth (0.8.1-1) lucid; urgency=low

  [ Scott James Remnant ]
  * Update to the upstream 0.8.1 release:
    - Our patches have been merged upstream, some changes due to cleaning
      them up for submission and noticing a few bugs along the way.
      Remaining changes are:
      + ubuntu-logo theme
      + ubuntu version of the text theme
      + call update-initramfs rather than plymouth-update-initrd in
        plymouth-set-default-theme
      + filter fsck progress updates from the progress bar tracker
      + watch for enter key press
      + support lbm-nouveau as an alternate driver name for nouveau to
        permit backports once Lucid has released
      + use /dev/fb0 as default framebuffer device name
      + stop animation of script plugin in idle function
    - Will become process group leader of its VT if possible (opens without
      O_NOCTTY when redirecting stdio to it), this is almost certainly
      correct keyboard-wise.
    - Deallocates VT on "plymouth quit" after switching VT back to VT1
    - Open terminal in text and details plugin, don't assume it's already
      open.
    - Calling "plymouth quit" or "plymouth deactivate" while the same
      command is already running will now block the new command until the
      old one complete, rather than returning immediately.
    - Various window fixes for script plugin
    - Script plugin updated to use the window X and Y offsets every time
    - Plymouth client tool has been updated to have commands for many cases
      in preference to the --command style.

  * Restored code to disable Plymouth's graphical plugins when an alternate
    init= is given on the kernel command-line, otherwise init=/bin/bash
    doesn't work so well when Plymouth is in the initramfs.
  * Restored crash handler that dumps boot messages to /dev/tty1.

  * Split themes out into different packages, reducing the size of the
    Plymouth package. This also means that you can remove the themes
    packages to remove the "graphical splash" part of Plymouth while keeping
    the ability to prompt for questions on the console.
  * Use the alternatives system to select the default themes. The existing
    symlink will be replaced on upgrade if you have not changed it.
  * Also use alternatives to select the text theme.
  * Restore the upstream text theme, renaming ours to "ubuntu-text".
  * Fallback to the built-in details theme (boot messages on console, but
    with the ability to prompt for questions) if no theme package is
    installed.
  (LP: #507238)

    Unfortunately these changes mean that if you've selected a custom
    theme, you will need to install that package and select it again.
    Sorry about that.

  * Include the 16-color VGA frame-buffer renderer. LP: #526892.

  * Fix text, ubuntu-text and details themes to restore the console to text
    mode when adding text displays.

  * debian/rules:
    - Set default tty for boot and shutdown with configure arguments
    - Set default background color to the Ubuntu Aubergine, this provides
      some consistency with other default themes.
  * debian/plymouth.upstart, d...