Added a test case for bug #20528.

ext/pcre/tests/bug20528.phpt

@@ -0,0 +1,30 @@
+--TEST--
+preg_split() bug #20528
+--SKIPIF--
+<?php
+	if (!extension_loaded("pcre")) {
+		die("skip pcre extension is not available");
+	}
+?>
+--FILE--
+<?php
+	$data = '(#11/19/2002#)';
+	var_dump(preg_split('/\b/', $data));
+?>
+--EXPECT--
+array(7) {
+  [0]=>
+  string(2) "(#"
+  [1]=>
+  string(2) "11"
+  [2]=>
+  string(1) "/"
+  [3]=>
+  string(2) "19"
+  [4]=>
+  string(1) "/"
+  [5]=>
+  string(4) "2002"
+  [6]=>
+  string(2) "#)"
+}