Duplicate call to connection_mark_for_close
catched that warning (for the 1st time IIRC) at a hardened stable Gentoo Linux exit relay with LibreSSL 2.6.5:
Jul 21 08:02:55.000 [warn] connection_mark_for_close_internal_(): Bug: Duplicate call to connection_mark_for_close at src/or/directory.c:5204 (first at src/or/main.c
:1210) (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] tor_bug_occurred_(): Bug: src/or/connection.c:841: connection_mark_for_close_internal_: This line should not have been reached. (Future in
stances of this warning will be silenced.) (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: Line unexpectedly reached at connection_mark_for_close_internal_ at src/or/connection.c:841. Stack trace: (on Tor 0.3.4.5-rc 673f3d64
0ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(log_backtrace+0x43) [0x564c703385b3] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(tor_bug_occurred_+0xb9) [0x564c70353419] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(connection_dir_finished_flushing+0x99) [0x564c702ee739] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(connection_handle_read+0xb06) [0x564c702c7df6] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(+0x5211e) [0x564c7021511e] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/lib64/libevent-2.1.so.6(+0x2259d) [0x7fd546aa759d] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/lib64/libevent-2.1.so.6(event_base_loop+0x4e7) [0x7fd546aa8367] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(do_main_loop+0x17a) [0x564c7021733a] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(tor_run_main+0x1015) [0x564c70219725] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(tor_main+0x3a) [0x564c70211bba] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(main+0x19) [0x564c70211949] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /lib64/libc.so.6(__libc_start_main+0xea) [0x7fd545829eda] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)
Jul 21 08:02:55.000 [warn] Bug: /usr/bin/tor(_start+0x2a) [0x564c7021199a] (on Tor 0.3.4.5-rc 673f3d640ef7fb05)