I think this is a problem with any multilink field.

The following patch to roundup/cgi/templating.py I think fixes it

         for name in self._props.keys():
             if name not in exclude:
-                query[name] = self[name].plain()
+                prop = self._props[name]
+                if not isinstance(prop, hyperdb.Multilink):
+                    query[name] = self[name].plain()
+                else:
+                    query[name] =
",".join(self._klass.get(self._nodeid, name))
+
         return self._classname + "?" + "&".join(

If it's not a multilink then copy the attributes across as it
does currently. If it's a multilink, get the list of multilink
values from the database and turn it into a comma separated list.

AFAIK, copy_url always works with the data from the database
and not any changes done to the form displaying the "Make a copy"
url. Can anybody confirm this assumption?

If my assumption is correct, I will check in this change for further
testing and release on the next release cycle.