Description of problem:

Mock fails to build epel-5 due to wrong arguments passed to usermod
Please do not confuse this bug with: https://bugzilla.redhat.com/show_bug.cgi?id=1535328


Version-Release number of selected component (if applicable):
[mshipper@vbox-dev tmp]$ cat /etc/redhat-release 
CentOS Linux release 7.4.1708 (Core) 
[mshipper@vbox-dev tmp]$ rpm -qi mock
Name        : mock
Version     : 1.4.8
Release     : 1.el7
Architecture: noarch
Install Date: Thu 25 Jan 2018 08:21:36 PM CST
Group       : Unspecified
Size        : 442065
License     : GPLv2+
Signature   : RSA/SHA256, Fri 22 Dec 2017 06:57:14 AM CST, Key ID 6a2faea2352c64e5
Source RPM  : mock-1.4.8-1.el7.src.rpm
Build Date  : Fri 22 Dec 2017 06:38:41 AM CST
Build Host  : buildvm-ppc64le-08.ppc.fedoraproject.org
Relocations : (not relocatable)
Packager    : Fedora Project
Vendor      : Fedora Project
URL         : https://github.com/rpm-software-management/mock/
Summary     : Builds packages inside chroots
Description :
Mock takes an SRPM and builds it in a chroot.

How reproducible:
100%

Steps to Reproduce:
1. mock -r /etc/mock/epel-5-x86_64.cfg --scrub=root-cache --scrub=c-cache --scrub=cache --scrub=yum-cache --scrub=chroot
2. mock -r /etc/mock/epel-5-x86_64.cfg --init
3. mock -r /etc/mock/epel-5-x86_64.cfg -i vim


Actual results:
mshipper@vbox-dev charter-it-telemetrylander]$ mock -r /etc/mock/epel-5-x86_64.cfg -i vim
INFO: mock.py version 1.4.8 starting (python version = 2.7.5)...
Start: init plugins
INFO: selinux disabled
Finish: init plugins
Start: run
Start: chroot init
INFO: calling preinit hooks
INFO: enabled root cache
INFO: enabled yum cache
Start: cleaning yum metadata
Finish: cleaning yum metadata
INFO: enabled HW Info plugin
Mock Version: 1.4.8
INFO: Mock Version: 1.4.8
ERROR: Command failed: 
 # /usr/bin/systemd-nspawn -q -M 2b9b4b1e880d49f98f387a9999682e61 -D /var/lib/mock/epel-5-x86_64/root --setenv=LANG=en_US.UTF-8 --setenv=TERM=vt100 --setenv=SHELL=/bin/bash --setenv=HOSTNAME=mock --setenv=PROMPT_COMMAND=printf "\033]0;<mock-chroot>\007" --setenv=HOME=/builddir --setenv=PATH=/usr/bin:/bin:/usr/sbin:/sbin --setenv=PS1=<mock-chroot> \s-\v\$  /usr/sbin/usermod --non-unique -u 1000 mockbuild

Expected results:
The package is expected to install

Additional info:
I am not sure if this is a new bug or the fix was not pushed into epel?