Comment (by Roland Haas):

A bug, but has been there for a long time. Since it will affect the how surfaces are used by existing runs, will be addressed after the ET_2020_05 release and backported if found to not be too disruptive to code relying on the (erroneous) behaviour.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2337/ahfinderdirect-does-not-mark-surfaces-as