Once upgraded to CentOS 8, the default python env (both of runtime and
build container) is python3.
It fails to build platform-kickstart rpm for the changes of function
'subprocess.check_output' during upgrading from python2 to python3.
In python3.5 or above the default output format of function
'subprocess.check_output', which is str in python2, is bytes. However if
factor 'universal_newlines' is set as True, the output format will be
str in both python3 and python2.
Setting "universal_newlines=True" is safe for current system and can
solve issues met in python3.
Change-Id: I01b166b5669553d9363b745747e1e9901345904f
Story: 2007018
Task: 37803
Signed-off-by: SidneyAn <ran1.an@intel.com>
cdabacd300