[ruby/date] Anchor at beginning of numbers

https://hackerone.com/reports/1254844

https://github.com/ruby/date/commit/2f7814cc22

ext/date/date_parse.c

@@ -980,7 +980,7 @@ parse_iso(VALUE str, VALUE hash)
 {
     static const char pat_source[] =
 #ifndef TIGHT_PARSER
-	"('?[-+]?\\d+)-(\\d+)-('?-?\\d+)"
+	"('?[-+]?" NUMBER "+)-(\\d+)-('?-?\\d+)"
 #else
 	BOS
 	FPW_COM FPT_COM

test/date/test_date_parse.rb

@@ -590,6 +590,11 @@ class TestDateParse < Test::Unit::TestCase
     h = Timeout.timeout(1) {Date._parse(str)}
     assert_equal(100_000, Math.log10(h[:year]))
     assert_equal(1, h[:mon])
+
+    str = "Jan - 1" + "0" * 100_000
+    h = Timeout.timeout(1) {Date._parse(str)}
+    assert_equal(1, h[:mon])
+    assert_not_include(h, :year)
   end
 
   require 'time'