Consider the following simple hierarchy: a parent dynamic class and a single dynamic descendant from it. Whenever the descendant is referenced and then immediately unreferenced, the parent dynamic class does not get finalized.

Steps to reproduce:
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   1.   Consider dummy implementation of GTypePlugin interface, which does nothing, but sets the value of 'GTypeInfo *info' output parameter of the methods g_type_plugin_complete_type_info()' and 'g_type_plugin_complete_interface_info()', based on the value of passed in type ids.

   2. Also simple hierarchy of types is implemented:
          * Static fundamental "GTTPFSet" class.
          * Direct dynamic descendant of "GTTPFSet" - "GTTPDynSet" class.
          * Direct dynamic descendant of "GTTPDynSet" - "GTTPDynList" class, also implementing dynamic "GTTPIDynList" interface.

   3. All three dynamic types are explicitly registered via
      "g_type_register_dynamic()", using the same instance of GTypePlugin
      implementation from P.1.

   4. The class "GTTPDynList" is referenced once and then immediately
      unreferenced.


Debugging against Glib-GObject v.2.6.5 sources shows that during initialization of "GTTPDynList" descendant class, it's dynamic parent "GTTPDynSet" gets referenced twice. Possible solution may be eliminating this by adding some kind of "just_initialized" flag.