can be converted to float properly.

	* numeric.c (fix_fdiv): calls rb_big_fdiv when the given second
	  argument is a bignum.

	* rational.c (nurat_fdiv): should calculate Float(x/y), not
	  Float(x)/Float(y).



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@23726 b2dd03c8-39d4-4d8f-98ff-823fe69b080e