don't ignore [advancement] on unit construction.

src/unit.cpp

@@ -40,6 +40,8 @@
 
 #include <boost/bind.hpp>
 #include <boost/foreach.hpp>
+#include <boost/function_output_iterator.hpp>
+#include <boost/range/algorithm.hpp>
 
 static lg::log_domain log_unit("unit");
 #define DBG_UT LOG_STREAM(debug, log_unit)
@@ -411,6 +413,14 @@ unit::unit(const config &cfg, bool use_traits, const vconfig* vcfg) :
 		} while(++cfg_range.first != cfg_range.second);
 	}
 
+	//If cfg specifies [advancement]s, replace this [advancement]s with them.
+	if(cfg.has_child("advancement"))
+	{
+		cfg_.clear_children("advancement");
+		boost::copy( cfg.child_range("advancement")
+			, boost::make_function_output_iterator(boost::bind( &config::add_child, cfg_ /*thisptr*/, "advancement", _1 )) );
+	}
+
 	//don't use the unit_type's abilities if this config has its own defined
 	cfg_range = cfg.child_range("abilities");
 	if(cfg_range.first != cfg_range.second) {