ostree: Run commands in universal_newlines mode

This will mean the output is returned as unicode (decoded as UTF-8).
Thus Kobo will not have to do any decoding. This should work around
possible errors with breaking multibyte unicode character sequences into
different chunks.

Relates: https://pagure.io/releng/failed-composes/issue/237
Relates: https://github.com/release-engineering/kobo/issues/119
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_ostree_script.py

@@ -54,6 +54,7 @@ class OstreeTreeScriptTest(helpers.PungiTestCase):
                     logfile=self.topdir + "/logs/Atomic/create-ostree-repo.log",
                     show_cmd=True,
                     stdout=True,
+                    universal_newlines=True,
                 )
             ] + extra_calls
         )
@@ -113,6 +114,7 @@ class OstreeTreeScriptTest(helpers.PungiTestCase):
                     logfile=self.topdir + "/logs/Atomic/ostree-summary.log",
                     show_cmd=True,
                     stdout=True,
+                    universal_newlines=True,
                 )
             ]
         )