merge revision(s) r46547: [Backport #9976]

	* hash.c (env_aset, env_has_key, env_assoc, env_has_value),
	  (env_rassoc, env_key): prohibit tainted strings if $SAFE is
	  non-zero.  [Bug #9976]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@47346 b2dd03c8-39d4-4d8f-98ff-823fe69b080e