I spoke too soon. Just had a segmentation fault this morning on a server running the standard package 9.16.1-0ubuntu2.11 (so without Sergio's patches).

Syslog messages including recent DNS query log below:

Dec  5 11:13:02 ff0133 named[825]: client @0x7f487c0f8cc0 192.168.33.143#8873 (safebrowsing.googleapis.com): query: safebrowsing.googleapis.com IN TYPE65 + (192.168.33.3)
Dec  5 11:13:02 ff0133 named[825]: client @0x7f487c0f8cc0 192.168.33.105#55867 (star.c10r.facebook.com): query: star.c10r.facebook.com IN A + (192.168.33.3)
Dec  5 11:13:02 ff0133 named[825]: client @0x7f487816dcb0 192.168.33.117#53723 (lh3.googleusercontent.com): query: lh3.googleusercontent.com IN TYPE65 +T (192.168.33.3)
Dec  5 11:13:02 ff0133 named[825]: client @0x7f4874157130 192.168.33.117#53722 (lh3.googleusercontent.com): query: lh3.googleusercontent.com IN A +T (192.168.33.3)
Dec  5 11:13:02 ff0133 named[825]: client @0x7f4878010ef0 127.0.0.1#38013 (135.118.46.217.in-addr.arpa): query: 135.118.46.217.in-addr.arpa IN PTR + (127.0.0.1)
Dec  5 11:13:02 ff0133 named[825]: client @0x7f486c0e1920 192.168.33.134#50184 (tp.a40771798-frontier.imdb.com): query: tp.a40771798-frontier.imdb.com IN TYPE65 + (192.168.33.3)
Dec  5 11:13:02 ff0133 named[825]: client @0x7f486c0f4060 192.168.33.134#53467 (tp.a40771798-frontier.imdb.com): query: tp.a40771798-frontier.imdb.com IN A + (192.168.33.3)
Dec  5 11:13:02 ff0133 named[825]: client @0x7f487411adb0 192.168.33.134#53415 (d14x35054ycmgy.cloudfront.net): query: d14x35054ycmgy.cloudfront.net IN TYPE65 + (192.168.33.3)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f487816dcb0 192.168.33.117#53725 (lh5.googleusercontent.com): query: lh5.googleusercontent.com IN TYPE65 +T (192.168.33.3)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f4874157130 192.168.33.117#53724 (lh5.googleusercontent.com): query: lh5.googleusercontent.com IN A +T (192.168.33.3)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f4878010ef0 127.0.0.1#38060 (135.118.46.217.in-addr.arpa): query: 135.118.46.217.in-addr.arpa IN PTR + (127.0.0.1)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f4878010ef0 127.0.0.1#58461 (135.118.46.217.in-addr.arpa): query: 135.118.46.217.in-addr.arpa IN PTR + (127.0.0.1)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f486c0af250 127.0.0.1#39097 (135.118.46.217.in-addr.arpa): query: 135.118.46.217.in-addr.arpa IN PTR + (127.0.0.1)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f487816dcb0 192.168.33.117#53727 (www.rbs.co.uk): query: www.rbs.co.uk IN TYPE65 +T (192.168.33.3)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f4874157130 192.168.33.117#53726 (www.rbs.co.uk): query: www.rbs.co.uk IN A +T (192.168.33.3)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f487c178ea0 192.168.33.117#53729 (www.rbs.co.uk): query: www.rbs.co.uk IN TYPE65 +T (192.168.33.3)
Dec  5 11:13:03 ff0133 named[825]: client @0x7f487415f7d0 192.168.33.117#53728 (www.rbs.co.uk): query: www.rbs.co.uk IN A +T (192.168.33.3)
Dec  5 11:13:03 ff0133 kernel: [221093.288331] isc-worker0002[970]: segfault at 8 ip 00007f489451c166 sp 00007f488d848530 error 4 in libisc.so.1601.0.0[7f48944fa000+46000]
Dec  5 11:13:03 ff0133 kernel: [221093.288344] Code: 00 00 48 8d 3d ab b4 02 00 e8 66 39 fe ff 66 0f 1f 44 00 00 f3 0f 1e fa 41 57 41 56 41 55 41 54 55 53 48 83 ec 08 4c 8b 67 10 <41> 83 7c 24 08 02 0f 85 be 00 00 00 49 89 fd 49 8b 7c 24 10 48 89
Dec  5 11:13:19 ff0133 systemd[1]: named.service: Main process exited, code=killed, status=11/SEGV