conn_close_if_marked: Non-fatal assertion !(connection_is_writing(conn))

From tor-talk:

https://lists.torproject.org/pipermail/tor-talk/2018-September/044448.html

Sep 15 16:06:26.000 [warn] tor_bug_occurred_(): Bug: src/or/main.c:1044: conn_close_if_marked: Non-fatal assertion !(connection_is_writing(conn)) failed. (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug: Non-fatal assertion !(connection_is_writing(conn)) failed in conn_close_if_marked at src/or/main.c:1044. Stack trace: (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /usr/bin/tor(log_backtrace+0x47) [0x55727ae152e7] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /usr/bin/tor(tor_bug_occurred_+0xbd) [0x55727ae307ad] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /usr/bin/tor(+0x51b18) [0x55727acdbb18] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /lib64/libevent-2.1.so.6(+0x235b1) [0x7fb01de555b1] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug: /lib64/libevent-2.1.so.6(event_base_loop+0x537) [0x7fb01de55d47] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /usr/bin/tor(do_main_loop+0x209) [0x55727acde149] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /usr/bin/tor(tor_run_main+0x1015) [0x55727ace0835] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /usr/bin/tor(tor_main+0x3e) [0x55727acd868e] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /usr/bin/tor(main+0x1d) [0x55727acd841d] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug: /lib64/libc.so.6(__libc_start_main+0xeb) [0x7fb01c3d611b] (on Tor 0.3.4.8 da95b91355248ad8)
Sep 15 16:06:26.000 [warn] Bug:     /usr/bin/tor(_start+0x2a) [0x55727acd847a] (on Tor 0.3.4.8 da95b91355248ad8)