Fix: Blackholed request when POSTing to a URL with space

Eg:

Actual Posted URL:
    /admin/settings/settings/prefix/Access%20Control
$_GET value:
    /admin/settings/settings/prefix/Access_Control

Since $unsetUrl differs, the $_GET value will get copied in to
CakeRequest::$query, causing CakeRequest::here() to return:

    /admin/settings/settings/prefix/Access%20Control?%2Fadmin%2Fsettings%2Fsettings%2Fprefix%2FAccess_Control=

This confuses SecurityComponent in the following line:

    https://github.com/cakephp/cakephp/blob/f23d811ff59c50ef278e98bb75f4ec1e7e54a5b3/lib/Cake/Controller/Component/SecurityComponent.php#L514

lib/Cake/Network/CakeRequest.php

@@ -207,7 +207,7 @@ protected function _processGet() {
 			$query = $_GET;
 		}
 
-		$unsetUrl = '/' . str_replace('.', '_', urldecode($this->url));
+		$unsetUrl = '/' . str_replace(array('.', ' '), '_', urldecode($this->url));
 		unset($query[$unsetUrl]);
 		unset($query[$this->base . $unsetUrl]);
 		if (strpos($this->url, '?') !== false) {

lib/Cake/Test/Case/Network/CakeRequestTest.php

@@ -2144,6 +2144,20 @@ public function testHere() {
 		$this->assertEquals('/posts/base_path/1/name:value?test=value', $result);
 	}
 
+/**
+ * Test the here() with space in URL
+ *
+ * @return void
+ */
+	public function testHereWithSpaceInUrl() {
+		Configure::write('App.base', '');
+		$_GET = array('/admin/settings/settings/prefix/Access_Control' => '');
+		$request = new CakeRequest('/admin/settings/settings/prefix/Access%20Control');
+
+		$result = $request->here();
+		$this->assertEquals('/admin/settings/settings/prefix/Access%20Control', $result);
+	}
+
 /**
  * Test the input() method.
  *