merge revision(s) r47217: [Backport #10062]

	* ext/thread/thread.c (get_array): check instance variables are
	  initialized properly.  [ruby-core:63826][Bug #10062]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@47378 b2dd03c8-39d4-4d8f-98ff-823fe69b080e