Comment (by Roland Haas):

I am not sure exactly what is happening. I will have to add some debug code to check what is going on. Unfortunately the issue does not show up when compiling without optimization so I suspect that adding too much debug code may make the issue go away.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2426/g-10-possibly-miscompiles-parts-of-carpet