ActivityBundle: don't wrap the temporal icon path in a TempFilePath - SL #4276

In the Journal, CellRendererActivityIcon is calling its do_render
method after the temporal file is removed.  This is because we wrap
the icon path in a TempFilePath to control its deletion, but as we
don't maintain any reference to it, its __del__ method deletes the
temporal file.

Note that returning the path directly has one disadventage: the
temporal file is left in /tmp .

As a comment in the get_icon method of ActivityBundle say, ideally we
should return the icon data.  But that implies a major change in the
Journal model and views, and in the CellRendererIcon class.

Signed-off-by: Manuel Quiñones <manuq@laptop.org>
Acked-by: Simon Schampijer <simon@laptop.org>

src/sugar3/bundle/activitybundle.py

@@ -213,7 +213,7 @@ class ActivityBundle(Bundle):
                                                          suffix='.svg')
             os.write(temp_file, icon_data)
             os.close(temp_file)
-            return util.TempFilePath(temp_file_path)
+            return temp_file_path
 
     def get_activity_version(self):
         """Get the activity version"""