yeah silly me for believing the docstring that claims ```Formats the filesystem, unconditionatlly [sic].``` It actually means ```Almost never format the filesystem, even it's a different one then requested. Please wipe the blockdevice manually and try again.```

btw, is it possible that the check always fails because ```$self->{block_device}->has_filesystem``` is used instead of ```$self->{block_device}->has_filesystem()``` causing it to format as per docstring?