Fix KeyError#{key,receiver} of Thread#fetch

[ruby-core:84508] [Bug #14247]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61507 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_thread.rb

@@ -557,7 +557,9 @@ class TestThread < Test::Unit::TestCase
     assert_equal(3, t.fetch("qux") {x = 3})
     assert_equal(3, x)
 
-    assert_raise(KeyError) {t.fetch(:qux)}
+    e = assert_raise(KeyError) {t.fetch(:qux)}
+    assert_equal(:qux, e.key)
+    assert_equal(t, e.receiver)
   ensure
     t.kill if t
   end

thread.c

@@ -3168,7 +3168,7 @@ rb_thread_fetch(int argc, VALUE *argv, VALUE self)
 	return rb_yield(key);
     }
     else if (argc == 1) {
-	rb_raise(rb_eKeyError, "key not found: %"PRIsVALUE, key);
+	rb_key_err_raise(rb_sprintf("key not found: %+"PRIsVALUE, key), self, key);
     }
     else {
 	return argv[1];