image-fuzzer: Use io.StringIO

StringIO.StringIO is not available on Python 3, but io.StringIO
is available on both Python 2 and 3.  io.StringIO is slightly
different from the Python 2 StringIO module, though, so we need
bytes coming from subprocess.Popen() to be explicitly decoded.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20191016192430.25098-5-ehabkost@redhat.com
Message-Id: <20191016192430.25098-5-ehabkost@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
1 file changed