Raise exceptions when scopes and routes have conflicting parameters

Having a scope contain a route with different parameters is most likely
a mistake. In addition it will defeat optimizations for reverse routing.

src/Routing/ScopedRouteCollection.php

@@ -390,6 +390,19 @@ protected function _makeRoute($route, $defaults, $options) {
 
 			$route = str_replace('//', '/', $this->_path . $route);
 			if (is_array($defaults)) {
+				foreach ($this->_params as $param => $val) {
+					if (isset($defaults[$param]) && $defaults[$param] !== $val) {
+						$msg = 'You cannot define routes that conflict with the scope. ' .
+							'Scope had %s = %s, while route had %s = %s';
+						throw new Error\Exception(sprintf(
+							$msg,
+							$param,
+							$val,
+							$param,
+							$defaults[$param]
+						));
+					}
+				}
 				$defaults += $this->_params;
 			}
 			$route = new $routeClass($route, $defaults, $options);

tests/TestCase/Routing/ScopedRouteCollectionTest.php

@@ -166,6 +166,18 @@ public function testConnectErrorInvalidRouteClass() {
 		$routes->connect('/:controller', [], ['routeClass' => '\StdClass']);
 	}
 
+/**
+ * Test conflicting parameters raises an exception.
+ *
+ * @expectedException \Cake\Error\Exception
+ * @expectedExceptionMessage You cannot define routes that conflict with the scope.
+ * @return void
+ */
+	public function testConnectConflictingParameters() {
+		$routes = new ScopedRouteCollection('/admin', ['prefix' => 'admin'], []);
+		$routes->connect('/', ['prefix' => 'manager', 'controller' => 'Dashboard', 'action' => 'view']);
+	}
+
 /**
  * Test connecting redirect routes.
  *