Time zone is not set correctly using TZ environment variable, see the output below:

[root@linux dev]# docker exec -ti zabbix-web bash
bash-4.3# date
Wed May 10 12:23:36 GMT 2017
bash-4.3# export
...
declare -x TZ="Europe/Ljubljana"
...
declare -x ZBX_SOURCES="svn://svn.zabbix.com/tags/3.2.5/"
declare -x ZBX_VERSION="3.2.5"
bash-4.3#

Solution is to include tzdata package in Docker image.