cont.c (rb_fiber_atfork): th->root_fiber may not exist
Otherwise, bootstraptest/test_fork.rb fails with -DVM_CHECK_MODE=2
[Bug #15041]
Fixes: r64589 "cont.c: set th->root_fiber to current fiber at fork"
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64593 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
cont.c (rb_fiber_atfork): th->root_fiber may not exist
Otherwise, bootstraptest/test_fork.rb fails with -DVM_CHECK_MODE=2
[Bug #15041]
Fixes: r64589 "cont.c: set th->root_fiber to current fiber at fork"
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64593 b2dd03c8-39d4-4d8f-98ff-823fe69b080e