Refs #11432. Reverting change that breaks compilation on RHEL6

Code/Mantid/Framework/PythonInterface/mantid/geometry/src/Exports/SpaceGroup.cpp

@@ -47,6 +47,7 @@ namespace //<unnamed>
 
 void export_SpaceGroup()
 {
+  register_ptr_to_python<boost::shared_ptr<SpaceGroup> >();
   register_ptr_to_python<boost::shared_ptr<const SpaceGroup> >();
 
   class_<SpaceGroup, boost::noncopyable, bases<Group> >("SpaceGroup", no_init)

Code/Mantid/Framework/PythonInterface/mantid/geometry/src/Exports/SpaceGroupFactory.cpp

@@ -30,9 +30,10 @@ namespace
         return self.isSubscribed(number);
     }
 
-    SpaceGroup_const_sptr createSpaceGroup(SpaceGroupFactoryImpl &self, const std::string &symbol)
+    SpaceGroup_sptr createSpaceGroup(SpaceGroupFactoryImpl &self, const std::string &symbol)
     {
-        return self.createSpaceGroup(symbol);
+        SpaceGroup_const_sptr spaceGroup = self.createSpaceGroup(symbol);
+        return boost::const_pointer_cast<SpaceGroup>(spaceGroup);
     }
 
 }