Bug: Assertion cmux failed in circuitmux_get_policy at src/or/circuitmux.c

This was triggered during an heavy load on my relay for which all the RAM and disk space has been consumed:

Dec 15 20:44:20.612 [err] tor_assertion_failed_(): Bug: src/or/circuitmux.c:630: circuitmux_get_policy: Assertion cmux failed; aborting. (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug: Assertion cmux failed in circuitmux_get_policy at src/or/circuitmux.c:630. Stack trace: (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(log_backtrace+0x42) [0x55cac920c342] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(tor_assertion_failed_+0x8d) [0x55cac922768d] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(circuitmux_get_policy+0x57) [0x55cac9167d57] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(+0xb7f41) [0x55cac913ff41] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(smartlist_pqueue_pop+0x156) [0x55cac9217196] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(+0xb9d7e) [0x55cac9141d7e] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(+0xb805f) [0x55cac914005f] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /usr/lib/x86_64-linux-gnu/libevent-2.0.so.5(event_base_loop+0x819) [0x7f38ac2544c9] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(do_main_loop+0x24f) [0x55cac90db53f] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(tor_run_main+0x265) [0x55cac90dc9c5] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(tor_main+0x3a) [0x55cac90d621a] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(main+0x19) [0x55cac90d5f89] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7f38aaf6d830] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)
Dec 15 20:44:20.678 [err] Bug:     /home/relay/tor/src/or/tor(_start+0x29) [0x55cac90d5fd9] (on Tor 0.3.3.0-alpha-dev b1682551a6860a2b)