process_damage_region can run from a timer, so the window may have be…

…en unmanaged since it was scheduled - avoid printing a warning in this case

git-svn-id: https://xpra.org/svn/Xpra/trunk@3072 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/window_source.py

@@ -766,7 +766,7 @@ def process_damage_region(self, damage_time, window, x, y, w, h, coding, options
         if w==0 or h==0:
             return
         if not window.is_managed():
-            warn("the window %s is not composited!?", window)
+            debug("the window %s is not composited!?", window)
             return
         # It's important to acknowledge changes *before* we extract them,
         # to avoid a race condition.