stable_topsort.patch

diff --git a/lib/galaxy/util/topsort.py b/lib/galaxy/util/topsort.py
index 80c6bd3..84cedae 100644
--- a/lib/galaxy/util/topsort.py
+++ b/lib/galaxy/util/topsort.py
@@ -31,9 +31,10 @@ then CycleError is raised, and the exception object supports
 many methods to help analyze and break the cycles.  This requires
 a good deal more code than topsort itself!
 """
-
+from collections import OrderedDict
 from exceptions import Exception
 
+
 class CycleError(Exception):
     def __init__(self, sofar, numpreds, succs):
         Exception.__init__(self, "cycle in constraints",
@@ -124,8 +125,8 @@ class CycleError(Exception):
         return answer
 
 def topsort(pairlist):
-    numpreds = {}   # elt -> # of predecessors
-    successors = {} # elt -> list of successors
+    numpreds = OrderedDict()   # elt -> # of predecessors
+    successors = OrderedDict() # elt -> list of successors
     for first, second in pairlist:
         # make sure every elt is a key in numpreds
         if not numpreds.has_key(first):