For ReMap to work, S has to be marked volatile :/.

apt-pkg/cacheiterators.h

@@ -57,7 +57,7 @@ template<typename Str, typename Itr> class pkgCache::Iterator :
 	Str* OwnerPointer() const { return static_cast<Itr const*>(this)->OwnerPointer(); }
 
 	protected:
-	Str *S;
+	Str *volatile S;
 	pkgCache *Owner;
 
 	public: