Off-by-one error in passwd 0.68 and earlier, when using the --stdin option, causes passwd to use the first 78 characters of a password inst…

Off-by-one error in passwd 0.68 and earlier, when using the --stdin option, causes passwd to use the first 78 characters of a password instead of the first 79, which results in a small reduction of the search space required for brute force attacks.