If user uses locale like cs_CZ.UTF-8 and sudo is configred to use passwd_timeout to seconds, like 0.1 = 6s. sudo command uses user's locale to parse this number and prints error message.

Steps to Reproduce:
1. # echo "Defaults passwd_timeout = 0.1" >> /etc/sudoers
2. $ LANG=cs_CZ.UTF-8 sudo bash

Actual results:
$ LANG=cs_CZ.UTF-8 sudo bash
sudo: value `0.1' is invalid for option `passwd_timeout'
[sudo] password for test:

Expected results:
$ LANG=cs_CZ.UTF-8 sudo bash
[sudo] password for test:

Tested on the latest stable release. I also tried to set sudoers_locale but it had no effect on this issue.