Ooops, bugfix.

lib/Context.php

@@ -23,6 +23,16 @@ class Context
         $this->configure();
     }
 
+    public function setShell(Shell $shell)
+    {
+        $this->shell = $shell;
+    }
+
+    public function getShell()
+    {
+        return $this->shell;
+    }
+
     public function setParent(Context $parent=null)
     {
         $this->parent = $parent;