Comment 4 for bug 1445630

Workaround by @8-mail-g worked for me. This question http://askubuntu.com/questions/597333/get-wifi-password-into-ubuntu-touch suggests it's because of a timeout occurring before the password was entered. Maybe on the coding side, this can be prevented by saving the password temporarily and retrying the same password a second time upon a single failure, if the reason for failure was a timeout?