I now managed to get it crashing too.
I tried some tricks to get a coredump, without luck. I then ran strace -f to see what happens before the crash:
19962 gettimeofday({1462779387, 327340}, NULL) = 0
19962 gettimeofday({1462779387, 327428}, NULL) = 0
19962 gettimeofday({1462779387, 327587}, NULL) = 0
19962 gettimeofday({1462779387, 328128}, NULL) = 0
19962 gettimeofday({1462779387, 328224}, NULL) = 0
19962 stat("/home/zope/bla2/eggs/plone.app.layout-2.5.19-py2.7.egg/plone/app/layout/viewlets/sections.pt", {st_mode=S_IFREG|0644, st_size=1735, ...}) = 0
19962 stat("/home/zope/bla2/eggs/plone.app.layout-2.5.19-py2.7.egg/plone/app/layout/viewlets/globalstatusmessage.pt", {st_mode=S_IFREG|0644, st_size=480, ...}) = 0
19962 stat("/home/zope/bla2/eggs/plone.app.layout-2.5.19-py2.7.egg/plone/app/layout/viewlets/path_bar.pt", {st_mode=S_IFREG|0644, st_size=1181, ...}) = 0
19962 stat("/home/zope/bla2/eggs/plone.locking-2.1.1-py2.7.egg/plone/locking/browser/info.pt", {st_mode=S_IFREG|0644, st_size=1838, ...}) = 0
19962 stat("/home/zope/bla2/eggs/plone.app.layout-2.5.19-py2.7.egg/plone/app/layout/viewlets/social_tags_body.pt", {st_mode=S_IFREG|0644, st_size=252, ...}) = 0
19962 stat("/home/zope/bla2/eggs/plone.app.layout-2.5.19-py2.7.egg/plone/app/layout/viewlets/toc.pt", {st_mode=S_IFREG|0644, st_size=336, ...}) = 0
19962 gettimeofday({1462779387, 360070}, NULL) = 0
19962 --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x80} ---
19961 +++ killed by SIGSEGV +++
19962 +++ killed by SIGSEGV +++
19955 +++ killed by SIGSEGV +++
19952 <... wait4 resumed> [{WIFSIGNALED(s) && WTERMSIG(s) == SIGSEGV}], 0, NULL) = 19955
19952 --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_KILLED, si_pid=19955, si_uid=1001, si_status=SIGSEGV, si_utime=1880, si_stime=622} ---
19952 rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7fbbf38643d0}, {0x53c2a0, [], SA_RESTORER, 0x7fbbf38643d0}, 8) = 0
19952 close(12) = 0
19952 exit_group(-11) = ?
19952 +++ exited with 245 +++
This is always the same ending, toc.pt is always the last file getting stated. Unfortunately, the execption is quite generic. I won't start relearning gdb here, because I don't actually use Ubuntu myself at the moment.