Recursive things are exclusively magical.

...  Magically delicious, even.

includes/tuque_wrapper.inc

@@ -166,6 +166,10 @@ class IslandoraFedoraObject extends FedoraObject {
   public function __set($name, $value) {
     parent::__set($name, $value);
 
+    // Recursion only matters for magic properties... "Plain" properties cannot
+    // call other code in order to start recursing, and in fact we would get
+    // stuck looping with a "plain" property.
+    if ($this->propertyIsMagical($name)) {
       // XXX: Due to the structure of the code, we cannot use property_exists()
       // (because many of the properties are declared in the class, and the magic
       // triggers due them being NULLed), nor can we use isset() (because it is
@@ -178,6 +182,7 @@ class IslandoraFedoraObject extends FedoraObject {
         $vars = get_object_vars($this);
       }
     }
+  }
 
   /**
    * Ingest the given datastream.
@@ -430,6 +435,10 @@ class IslandoraFedoraDatastream extends FedoraDatastream {
   public function __set($name, $value) {
     parent::__set($name, $value);
 
+    // Recursion only matters for magic properties... "Plain" properties cannot
+    // call other code in order to start recursing, and in fact we would get
+    // stuck looping with a "plain" property.
+    if ($this->propertyIsMagical($name)) {
       // XXX: Due to the structure of the code, we cannot use property_exists()
       // (because many of the properties are declared in the class, and the magic
       // triggers due them being NULLed), nor can we use isset() (because it is
@@ -442,6 +451,7 @@ class IslandoraFedoraDatastream extends FedoraDatastream {
         $vars = get_object_vars($this);
       }
     }
+  }
 
   /**
    * Inherits.