I noticed that French password prompts in `shell-mode' weren't detected
as such by `comint-watch-for-password-prompt' due to a space between the
password prompt and the colon (as in `Mot de passe :'), so I modified
`comint-password-prompt-regexp' to detect this space (as well as
non-breaking spaces before and after the colon, which is used by sudo).

Please let me know if I missed anything, as this is my first patch.
Thank you!