make upgrade process more forgiving: don't call InitTransient on objects until everything's upgraded

tpers.py

@@ -113,8 +113,7 @@ class TPrs(object):
         self._fWriteToPersistent = True
         if self._versionCurr != self._version:
             Odb.rgtprsToUpgrade.append(self)
-        with self.SetTransiently():
-            self.InitTransient()
+        Odb.rgtprsToInit.append(self)
     def _Upgrade(self):
         self.UpgradeFrom(self._versionCurr)
         self._versionCurr = self._version
@@ -128,6 +127,7 @@ class Odb(object):
     @classmethod
     def Load(cls, fn):
         cls.rgtprsToUpgrade = []
+        cls.rgtprsToInit = []
         try:
             with open(fn, "r") as fl:
                 tprs = cPickle.load(fl)
@@ -135,13 +135,17 @@ class Odb(object):
             print "error unpickling:", e
             traceback.print_exc()
             return None
-        if len(cls.rgtprsToUpgrade) > 0:
         for tprsToUpgrade in cls.rgtprsToUpgrade:
             tprsToUpgrade._Upgrade()
+        for tprsToInit in cls.rgtprsToInit:
+            with tprsToInit.SetTransiently():
+                tprsToInit.InitTransient()
+        if len(cls.rgtprsToUpgrade) > 0:
             fnUpgraded = fn + ".upgraded"
             Odb.Save(tprs, fnUpgraded)
             tprs = Odb.Load(fnUpgraded)
         cls.rgtprsToUpgrade = None
+        cls.rgtprsToInit = None
         return tprs
 
 clsList = list