merge revision(s) 41250: [Backport #8516]

	* io.c (io_getc): fix 7bit coderange condition, check if ascii read
	  data instead of read length. [ruby-core:55444] [Bug #8516]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@41260 b2dd03c8-39d4-4d8f-98ff-823fe69b080e