stringio.c: don't raise after close

* ext/stringio/stringio.c (strio_close): don't raise on dobule
  close for consistent to IO#close.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49905 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Mon Mar  9 16:34:36 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/stringio/stringio.c (strio_close): don't raise on dobule
+	  close for consistent to IO#close.
+
 Mon Mar 09 06:44:48 2015  Koichi Sasada  <ko1@atdot.net>
 
 	* vm_insnhelper.h: define struct SVAR for SVAR.

ext/stringio/stringio.c

@@ -346,9 +346,6 @@ static VALUE
 strio_close(VALUE self)
 {
     StringIO(self);
-    if (CLOSED(self)) {
-	rb_raise(rb_eIOError, "closed stream");
-    }
     RBASIC(self)->flags &= ~STRIO_READWRITE;
     return Qnil;
 }

test/stringio/test_stringio.rb

@@ -193,12 +193,12 @@ class TestStringIO < Test::Unit::TestCase
   def test_close
     f = StringIO.new("")
     f.close
-    assert_raise(IOError) { f.close }
+    assert_nil(f.close)
 
     f = StringIO.new("")
     f.close_read
     f.close_write
-    assert_raise(IOError) { f.close }
+    assert_nil(f.close)
   ensure
     f.close unless f.closed?
   end