guest: Never use vmvga if host is RHEL (bz 1147662)

We basically need to do this independent of whether the build is configured
for RHEL defaults or not

tests/xmlconfig.py

@@ -318,12 +318,12 @@ class TestXMLMisc(unittest.TestCase):
         g = _make_guest(conn=conn)
 
         try:
-            cliconfig.stable_defaults = True
             g.emulator = "/usr/libexec/qemu-kvm"
             g.add_default_video_device()
-
             g.os_variant = "ubuntu13.10"
-            g.get_install_xml(True)
+
+            self._compare(g, "install-novmvga-rhel", True)
+            cliconfig.stable_defaults = True
             self._compare(g, "install-novmvga-rhel", True)
         finally:
             cliconfig.stable_defaults = False

virtinst/connection.py

@@ -327,8 +327,14 @@ class VirtualConnection(object):
                 self._conn_version = self._libvirtconn.getVersion()
         return self._conn_version
 
-    def stable_defaults(self, emulator=None):
-        if not cliconfig.stable_defaults:
+    def stable_defaults(self, emulator=None, force=False):
+        """
+        :param force: Just check if we are running on RHEL, regardless of
+            whether stable defaults are requested by the build. This is needed
+            to ensure we don't enable VM devices that are compiled out on
+            RHEL, like vmvga
+        """
+        if not cliconfig.stable_defaults and not force:
             return False
 
         if not self.is_qemu_system():

virtinst/guest.py

@@ -563,8 +563,8 @@ class Guest(XMLBuilder):
     # Device defaults #
     ###################
 
-    def stable_defaults(self):
-        return self.conn.stable_defaults(self.emulator)
+    def stable_defaults(self, *args, **kwargs):
+        return self.conn.stable_defaults(self.emulator, *args, **kwargs)
 
     def add_default_input_device(self):
         if self.os.is_container():
@@ -1066,8 +1066,9 @@ class Guest(XMLBuilder):
             self._add_spice_usbredir()
 
         video_model = self._os_object.get_videomodel(self)
-        if self.stable_defaults() and video_model == 'vmvga':
+        if video_model == 'vmvga' and self.stable_defaults(force=True):
             video_model = 'vga'
+
         for video in self.get_devices("video"):
             if video.model == video.MODEL_DEFAULT:
                 video.model = video_model