Full disk encryption passphrase is using wrong locale

When installing from the Xenial 16.04 media (amd64), if the language selected at the first step (before Ubiquity kicks in) is english and is then changed to another language (french in this situation), the whole installation process will proceed in french, all text entered in the field will be french, but the passphrase entered for the full disk encryption will be keyed in using the initial language, i.e. english.

If the user enters Canonical in the field, the value fowarded to Luks to create the passphrase will be Cqnonicql even though the rest of the typed text will be entered correctly.

This has the ackward result of blocking the boot sequence after installation unless the selected passphrase only has letters that do not change position depending on the locale. Entering the english-localized letters allow the user to boot correctly.

How to reproduce :
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Install using the 16.04 iso
Select english at the very first menu selection where this is displayed :

 Try Ubuntu without installing
        Install Ubuntu
    Check disk for defects
         Test memory
  Boot from first hard disk

Then choose "Install Ubuntu"

In the Welcome section of Ubiquity (graphical installer), change the language to french and proceed with a normal installation and select LVM and full disk encryption

Use aAa as the full disk encryption passphrase

After reboot, using aAa as the passphrase will not unlock the boot disk. qQq must be used.