test String#each_line when separator is longer than string.

Thanks Charles Nutter.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36648 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_string.rb

@@ -647,6 +647,13 @@ class TestString < Test::Unit::TestCase
     assert_equal(S("hello!"), res[0])
     assert_equal(S("world"),  res[1])
 
+    $/ = "ab"
+
+    res=[]
+    S("a").lines.each {|x| res << x}
+    assert_equal(1, res.size)
+    assert_equal(S("a"), res[0])
+
     $/ = save
 
     s = nil