Tails

It looks like this:

def electrum_config_is_persistent():
    filesystem = sh.findmnt('--noheadings',
                            '--output', 'SOURCE',
                            '--target', CONF_DIR).stdout.decode().strip()
    return filesystem in sh.glob('/dev/mapper/TailsData_unlocked[/electrum]')

It does not make sense to do that glob expansion, which will try to match against these:

• /dev/mapper/TailsData_unlocked/
• /dev/mapper/TailsData_unlockede
• …
• /dev/mapper/TailsData_unlockedu
• /dev/mapper/TailsData_unlockedm

of which none will match anything. Due to a bug in stretch’s python3-sh (version 1.11-1) sh.glob(e) returns e when there is no match, but it should clearly return the empty list, which it does in buster’s version (1.12.14-1.1). The correct check is filesystem == '/dev/mapper/TailsData_unlocked[/electrum]', and that the old check works in stretch is just a coincidence due to that bug.