merge revision(s) 1613917ae64: [Backport #15784]
Defer setting gc_stress instead of setting dont_gc [Bug #15784]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@67777 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 1613917ae64: [Backport #15784]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@67777 b2dd03c8-39d4-4d8f-98ff-823fe69b080e