Otherwise readline decides to initialize terminal handling at the first
readline call, and if that happens at the point it sees our
non-echoing rl_redisplay.

At that point, unless already intialized, readline wrongly convinces itself we
do our own handling of terminal peculiarities (such as cursor movement, or
erases).  We do not -- we merely wrap the stock rl_redisplay(), temporarily
hiding the actual characters.

The rl_initialize() in nmc_readline_echo()s fixes broken line editing in
password prompts that weren't preceded a previous non-password prompt.
The other one is there for consistency only. (I guess we should be
initializing readline before use anyway; although it seems to initialize
itself anyway if we fail to do so...)

https://github.com/NetworkManager/NetworkManager/pull/241