Misc/NEWS.d/next/Core and Builtins/2018-05-23-20-46-14.bpo-33622.xPucO9.rst

Fixed a leak when the garbage collector fails to add an object with the
``__del__`` method or referenced by it into the :data:`gc.garbage` list.
:c:func:`PyGC_Collect` can now be called when an exception is set and
preserves it.