tests: change blackbox test to work cross platform
While it is not easy to make a file 000 on Windows, you can
emulate most of the behaviors by replacing the file with a directory.
Also corrects test description to properly indicate that failing to
read from the log is fatal.
FROM centos:centos7
RUN yum install -y gcc
RUN yum install -y python-devel python-docutils
RUN yum install -y make
RUN yum install -y rpm-build
RUN yum install -y gettext
RUN yum install -y tar
# For creating repo meta data
RUN yum install -y createrepo