Invert exception types in the exception specification corresponding to |import dbus; ...stuff that might throw a dbus exception| so that failure to import dbus will be caught, rather than triggering a "NameError: name 'dbus' is not defined" error. Followup to bug 981146, r=trivial

--HG--
extra : rebase_source : f3439471f361ea16f74161a3ee68b9227e2c0eb9

python/mozbuild/mozbuild/mach_commands.py

@@ -412,7 +412,7 @@ class Build(MachCommandBase):
                         method = notify.get_dbus_method('Notify',
                                                         'org.freedesktop.Notifications')
                         method('Mozilla Build System', 0, '', 'Build complete', '', [], [], -1)
-                    except (dbus.exceptions.DBusException, ImportError):
+                    except (ImportError, dbus.exceptions.DBusException):
                         pass
 
             except (which.WhichError, ImportError):