The Rkhunter daily cron-job emails start like this:

/usr/bin/rkhunter: line 7439: [: too many arguments
/usr/bin/rkhunter: line 7439: [: too many arguments
Warning: The O/S name or version has changed since the last run:
         Old O/S value: openSUSE 20160222 (x86_64)    New value: openSUSE
20160225 (x86_64)
         Because of the change(s) the file properties checks may give some
false-positive results.
         You may need to re-run rkhunter with the '--propupd' option.

The warning is produced in line 7439 of /usr/bin/rkhunter:

                        if [ $PROG_VERS -lt $LATEST_VERS ]; then

PROG_VERS is extracted from language files here: /var/lib/rkhunter/db/i18n/*

The Turkish language file is detected as a binary file by grep. "sh -x
/usr/bin/rkhunter --update" shows the problematic call:

+ '[' Binary file /var/lib/rkhunter/db/i18n/tr matches -lt 2014030201 ']'
/usr/bin/rkhunter: line 7439: [: too many arguments

A simplified "grep" call shows the problem:

# grep Version /var/lib/rkhunter/db/i18n/tr
Binary file /var/lib/rkhunter/db/i18n/tr matches

The Grep option "--text" fixes the problem:

# grep --text Version /var/lib/rkhunter/db/i18n/tr
Version:2014030201