merge revision(s) 63252: [Backport #14707]

	string.c: fix scanned substring with `\K`

	* string.c (scan_once): fix the matched substring with `\K`, the
	  beginning of that string may differ from the matched position.
	  [ruby-core:86663] [Bug #14707]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@64320 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

string.c

@@ -8950,6 +8950,7 @@ scan_once(VALUE str, VALUE pat, long *start, int set_backref_str)
 	else {
 	    match = rb_backref_get();
 	    regs = RMATCH_REGS(match);
+	    pos = BEG(0);
 	    end = END(0);
 	}
 	if (pos == end) {

test/ruby/test_string.rb

@@ -1537,6 +1537,8 @@ def test_scan
     assert_nil($~)
 
     assert_equal(3, S("hello hello hello").scan("hello".taint).count(&:tainted?))
+
+    assert_equal(%w[1 2 3], S("a1 a2 a3").scan(/a\K./))
   end
 
   def test_size

version.h

@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.5.2"
 #define RUBY_RELEASE_DATE "2018-08-12"
-#define RUBY_PATCHLEVEL 67
+#define RUBY_PATCHLEVEL 68
 
 #define RUBY_RELEASE_YEAR 2018
 #define RUBY_RELEASE_MONTH 8