tests: fix qvm-copy-to-vm test

Make the check if remote file wasn't removed meaningful. Previously the
user didn't have permission to remote the source file, so even if the
tool would try, it would fail.

qubes/tests/integ/vm_qrexec_gui.py

@@ -943,11 +943,13 @@ class TC_00_AppVMMixin(object):
             self.testvm1.start(),
             self.testvm2.start()]))
 
+        self.loop.run_until_complete(self.testvm1.run_for_stdio(
+            'cp /etc/passwd /tmp/passwd'))
         with self.qrexec_policy('qubes.Filecopy', self.testvm1, self.testvm2):
             try:
                 self.loop.run_until_complete(
                     self.testvm1.run_for_stdio(
-                        'qvm-copy-to-vm {} /etc/passwd'.format(
+                        'qvm-copy-to-vm {} /tmp/passwd'.format(
                             self.testvm2.name)))
             except subprocess.CalledProcessError as e:
                 self.fail('qvm-copy-to-vm failed: {}'.format(e.stderr))
@@ -961,7 +963,7 @@ class TC_00_AppVMMixin(object):
 
         try:
             self.loop.run_until_complete(self.testvm1.run_for_stdio(
-                'test -f /etc/passwd'))
+                'test -f /tmp/passwd'))
         except subprocess.CalledProcessError:
             self.fail('source file got removed')