[tor-relays] [warn] Error relaying cell across rendezvous; closing circuits

I run the non-exit relay 8F6A78B1EA917F2BF221E87D14361C050A70CCC3 Today I noticed two [warn] lines in the Tor log file that I have not seen before:

[warn] Error relaying cell across rendezvous; closing circuits [warn] circuit_mark_for_close_(): Bug: Duplicate call to circuit_mark_for_close at ../src/core/or/command.c:577 (first at ../src/core/or/relay.c:343) (on Tor 0.4.8.12 )

I assume this is more of a FYI for the developers than for me as an operator. I'll keep an eye out to see if they appear more times.