sandbox_intern_string(): Bug: No interned sandbox parameter found for /etc/tor/torrc.d/

got this today at a stable hardened Gentoo linux server:

mr-fox ~ # cat x.log 
Jun 14 21:19:55.000 [warn] sandbox_intern_string(): Bug: No interned sandbox parameter found for /etc/tor/torrc.d/ (on Tor 0.3.1.3-alpha dc47d936d47ffc25)
Jun 14 21:19:55.000 [warn] sandbox_intern_string(): Bug: No interned sandbox parameter found for /etc/tor/torrc.d/ (on Tor 0.3.1.3-alpha dc47d936d47ffc25)

============================================================ T= 1497467995
(Sandbox) Caught a bad syscall attempt (syscall open)
/usr/bin/tor(+0x18e5f5)[0x55ec9b7a75f5]
/lib64/libc.so.6(opendir+0x11)[0x7f5dfe271421]
/lib64/libc.so.6(opendir+0x11)[0x7f5dfe271421]
/usr/bin/tor(tor_listdir+0x32)[0x55ec9b7a32e2]
/usr/bin/tor(+0x179080)[0x55ec9b792080]
/usr/bin/tor(config_get_lines_include+0x38)[0x55ec9b792258]
/usr/bin/tor(options_init_from_string+0x1df)[0x55ec9b716d0f]
/usr/bin/tor(options_init_from_torrc+0x1f1)[0x55ec9b717221]
/usr/bin/tor(+0x4f399)[0x55ec9b668399]
/usr/lib64/libevent-2.1.so.6(+0x23749)[0x7f5dff649749]
/usr/lib64/libevent-2.1.so.6(event_base_loop+0x57f)[0x7f5dff64a5ef]
/usr/bin/tor(do_main_loop+0x24d)[0x55ec9b66693d]
/usr/bin/tor(tor_main+0x1c3d)[0x55ec9b66a32d]
/usr/bin/tor(main+0x28)[0x55ec9b661d18]
/lib64/libc.so.6(__libc_start_main+0xfc)[0x7f5dfe1d972c]
/usr/bin/tor(_start+0x29)[0x55ec9b661d69]