It turns out this is because plymouth watch-keystroke in theory lets you listen for any keypress, but this does *not* work when the key you're waiting for is the enter key (at least, if you tell plymouth you're waiting for any key, 'enter' isn't registered). I think we probably want to fix this in plymouth so that the enter key can be used, rather than changing the message in casper.
It turns out this is because plymouth watch-keystroke in theory lets you listen for any keypress, but this does *not* work when the key you're waiting for is the enter key (at least, if you tell plymouth you're waiting for any key, 'enter' isn't registered). I think we probably want to fix this in plymouth so that the enter key can be used, rather than changing the message in casper.