Tails Installer cannot select an ISO in non-English locales

Originally created by @anonym on #15233 (Redmine)

Since Tails Installer 5.0.1 (introduced in Tails 3.2), when using a valid non-English locale (e.g. fr_FR.utf-8) the “select ISO” button remains inactive (greyed out) even when the “use a downloaded Tails ISO” radio button is selected.

You can run Tails Installer OK if you do:

`LANG=en_us tails-installer`

The problem:

def on_radio_button_source_iso_toggled(self, radio_button):
[...]
    if active_radio.get_label() == "Clone the current Tails":
[...]
    elif active_radio.get_label() == "Use a downloaded Tails ISO image":
[...]

The fix: translate those strings with _().

Feature Branch: installer:bugfix/15233-locale-fixes

Related issues

• Related to #15254 (closed)
• Related to #15416 (closed)
• Blocks #13245 (closed)