should not free local hook_list here.
exec_hooks_postcheck() clean executed hook_list if it is needed.
list_exec is freed if there are no events and this list is local
event (connected to specific iseq). However, iseq keeps to point
this local hook_list, freed list. To prevent this situation,
do not free hook_list here even if it has no events.
This issue is reported by @joker1007.
https://twitter.com/joker1007/status/1153649170797830144
Added by nagachika (Tomoyuki Chikanaga) over 4 years ago
merge revision(s) df317151a5b4e0c5a30fcc321a9dc6abad63f7ed: [Backport #16019]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67744 b2dd03c8-39d4-4d8f-98ff-823fe69b080e