Comment 2 for bug 1546673

Seeing this as well.

ii apache2 2.4.18-2ubuntu3.2 amd64 Apache HTTP Server

xdebug_llist_empty (l=l@entry=0x55aa254a4240, user=user@entry=0x0) at /build/xdebug-7LnU2E/xdebug-2.4.1/build-5.6/xdebug_llist.c:174
174 /build/xdebug-7LnU2E/xdebug-2.4.1/build-5.6/xdebug_llist.c: No such file or directory.
(gdb) backtrace
#0 xdebug_llist_empty (l=l@entry=0x55aa254a4240, user=user@entry=0x0) at /build/xdebug-7LnU2E/xdebug-2.4.1/build-5.6/xdebug_llist.c:174
#1 0x00007f088154b6d9 in xdebug_llist_destroy (l=0x55aa254a4240, user=user@entry=0x0) at /build/xdebug-7LnU2E/xdebug-2.4.1/build-5.6/xdebug_llist.c:180
#2 0x00007f088153ade8 in zm_post_zend_deactivate_xdebug () at /build/xdebug-7LnU2E/xdebug-2.4.1/build-5.6/xdebug.c:1233
#3 0x00007f08870e1afa in zend_post_deactivate_modules () from /usr/lib/apache2/modules/libphp5.6.so
#4 0x00007f0887074a65 in php_request_shutdown () from /usr/lib/apache2/modules/libphp5.6.so
#5 0x00007f088718aa37 in ?? () from /usr/lib/apache2/modules/libphp5.6.so
#6 0x000055aa23b46a40 in ap_run_handler ()
#7 0x000055aa23b46fc6 in ap_invoke_handler ()
#8 0x000055aa23b5d6ec in ap_internal_redirect ()
#9 0x00007f0882eaea92 in ?? () from /usr/lib/apache2/modules/mod_rewrite.so
#10 0x000055aa23b46a40 in ap_run_handler ()
#11 0x000055aa23b46fc6 in ap_invoke_handler ()
#12 0x000055aa23b5e462 in ap_process_async_request ()
#13 0x000055aa23b5e610 in ap_process_request ()
#14 0x000055aa23b5a6de in ?? ()
#15 0x000055aa23b509b0 in ap_run_process_connection ()
#16 0x00007f08876e37e9 in ?? () from /usr/lib/apache2/modules/mod_mpm_prefork.so
#17 0x00007f08876e3a74 in ?? () from /usr/lib/apache2/modules/mod_mpm_prefork.so
#18 0x00007f08876e48c5 in ?? () from /usr/lib/apache2/modules/mod_mpm_prefork.so
#19 0x000055aa23b293fe in ap_run_mpm ()
#20 0x000055aa23b22380 in main ()