FIX: Drop JoinNodes, fully specify regex

Author: effigies

nipype/pipeline/engine/utils.py

@@ -1050,7 +1050,17 @@ def make_field_func(*pair):
             expansions = defaultdict(list)
             for node in graph_in.nodes():
                 for src_id in list(old_edge_dict.keys()):
-                    if re.match(src_id + r'(\.[a-z]\d+)?$', node.itername):
+                    # Drop the original JoinNodes; only concerned with
+                    # generated Nodes
+                    if hasattr(node, 'joinfield'):
+                        continue
+                    # Patterns:
+                    #   - src_id : Non-iterable node
+                    #   - src_id.[a-z]\d+ : IdentityInterface w/ iterables
+                    #   - src_id.[a-z]I.[a-z]\d+ : Non-IdentityInterface w/ iterables
+                    #   - src_idJ\d+ : JoinNode(IdentityInterface)
+                    if re.match(src_id + r'((\.[a-z](I\.[a-z])?|J)\d+)?$',
+                                node.itername):
                         expansions[src_id].append(node)
             for in_id, in_nodes in list(expansions.items()):
                 logger.debug("The join node %s input %s was expanded"