tests: make tests not fail with substituted sys.stdout

At best lets skip tests in such a case.

qubesmgmt/tests/tools/qvm_run.py

@@ -22,12 +22,18 @@ import io
 import unittest.mock
 
 import subprocess
+import sys
 
 import qubesmgmt.tests
 import qubesmgmt.tools.qvm_run
 
 
 class TC_00_qvm_run(qubesmgmt.tests.QubesTestCase):
+    def setUp(self):
+        if sys.stdout is not sys.__stdout__ or \
+                sys.stderr is not sys.__stderr__:
+            self.skipTest('qvm-run change behavior on redirected stdout/stderr')
+        super(TC_00_qvm_run, self).setUp()
     def test_000_run_single(self):
         self.app.expected_calls[
             ('dom0', 'mgmt.vm.List', None, None)] = \

qubesmgmt/tests/tools/qvm_start_gui.py

@@ -48,7 +48,7 @@ class TC_00_qvm_start_gui(qubesmgmt.tests.QubesTestCase):
             b'KWIN_RUNNING = 0x1\n',
             b'access control enabled, only authorized clients can connect\n'
             b'SI:localuser:root\n'
-            b'SI:localuser:' + os.getlogin().encode() + b'\n',
+            b'SI:localuser:' + os.environ['USER'].encode() + b'\n',
         ]
 
         args = self.launcher.kde_guid_args(self.app.domains['test-vm'])