Hang on disconnecting RTSP clients on Gstreamer 1.18.0 (using test-video-disconnect example)

I'm trying to upgrade our Gstreamer applications from Gstreamer 1.14.4 to 1.18.0. After this upgrade, I see a hang when using gst-rtsp-server, in gst_rtsp_client_close when closing active clients.

This issue is reproducible on our installation by running the test-video-disconnect example, in the call to gst_rtsp_client_close. The full GDB stacktrace is pasted below. It does not occur on every run, but is hit most times.

With 1.14.4, this issue was not seen - test-video-disconnect runs fine, disconnecting the client successfully and exiting cleanly.

Is this a known issue in 1.18?

0x0000007ff7207270 in syscall () from /lib/libc.so.6
(gdb) bt
#0  0x0000007ff7207270 in syscall () from /lib/libc.so.
#1  0x0000007ff75de3f0 in g_mutex_lock_slowpath (mutex=0x57bd60)
    at ../glib/gthread-posix.c:1458
#2  0x0000007ff757f82c in g_source_unref_internal.lto_priv.63 (
    source=0x57bf60, context=0x57bd60, have_lock=0) at ../glib/gmain.c:2237
#3  0x0000007ff7c1503c in gst_rtsp_source_finalize (source=0x57d150)
    at ../gst-libs/gst/rtsp/gstrtspconnection.c:4152
#4  0x0000007ff757f824 in g_source_unref_internal.lto_priv.63 (
    source=0x57d150, context=0x57bd60, have_lock=0) at ../glib/gmain.c:2235
#5  0x0000007ff7f6e984 in gst_rtsp_client_close (client=0x57c190)
    at ../gst/rtsp-server/rtsp-client.c:1307
#6  0x0000007ff7f88120 in gst_rtsp_server_client_filter (
    server=server@entry=0x514910, func=func@entry=0x400f24 <client_filter>,
    user_data=0x422424b5b4a79e00, user_data@entry=0x0)
    at ../gst/rtsp-server/rtsp-server.c:1499
#7  0x0000000000401014 in shutdown_timeout (server=0x514910,
    server@entry=<error reading variable: value has been optimized out>)
    at test-video-disconnect.c:75
#8  0x0000007ff757da20 in g_timeout_dispatch (source=<optimized out>,
    callback=<optimized out>, user_data=<optimized out>)
    at ../glib/gmain.c:4800
#9  0x0000007ff758016c in g_main_dispatch (context=0x56d3b0)
--Type <RET> for more, q to quit, c to continue without paging--
    at ../glib/gmain.c:3309
#10 g_main_context_dispatch (context=context@entry=0x56d3b0)
    at ../glib/gmain.c:3974
#11 0x0000007ff7582d40 in g_main_context_iterate.isra.38 (context=0x56d3b0,
    block=block@entry=1, dispatch=dispatch@entry=1) at ../glib/gmain.c:4047
#12 0x0000007ff7584570 in g_main_loop_run (loop=loop@entry=0x431c10)
    at ../glib/gmain.c:4241
#13 0x00000000004010f4 in main (argc=<optimized out>, argv=<optimized out>)
    at test-video-disconnect.c:211

I've also raised this issue on the Gstreamer forums (http://gstreamer-devel.966125.n4.nabble.com/Hang-on-disconnecting-RTSP-clients-on-Gstreamer-1-18-0-using-test-video-disconnect-example-tt4695993.html#none) - but given this worked in 1.14.4 and now no longer works, I thought it made sense to raise a bug to track.

Thanks, Lawrence