string.c: chomp rs at the end

* string.c (rb_str_enumerate_lines): should chomp record separator
  only, but not a newline, at the end of the receiver as well as
  middle, if the separator is given.
  [ruby-core:84552] [Bug #14257]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61513 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

string.c

@@ -8012,7 +8012,12 @@ rb_str_enumerate_lines(int argc, VALUE *argv, VALUE str, VALUE ary)
 
     if (subptr != pend) {
 	if (chomp) {
-	    pend = chomp_newline(subptr, pend, enc);
+	    if (rsnewline) {
+		pend = chomp_newline(subptr, pend, enc);
+	    }
+	    else if (memcmp(pend - rslen, rsptr, rslen) == 0) {
+		pend -= rslen;
+	    }
 	}
 	line = rb_str_subseq(str, subptr - ptr, pend - subptr);
 	ENUM_ELEM(ary, line);

test/ruby/test_string.rb

@@ -1119,6 +1119,10 @@ CODE
     res = []
     S("\r\n").each_line(chomp: true) {|x| res << x}
     assert_equal([S("")], res)
+
+    res = []
+    S("a\n b\n").each_line(" ", chomp: true) {|x| res << x}
+    assert_equal([S("a\n"), S("b\n")], res)
   end
 
   def test_lines