SQUASH Apply part of first review

Mark a line to be folded back once migrated to python 3.
Make storage.database.manager's getFirstTID return the tid packed.
Also, update docstring to stop saying the result is unpacked.
Also, fix None handling in the storage.database.manager and in
master.transaction.

neo/master/transactions.py

@@ -215,7 +215,7 @@ class TransactionManager(EventQueue):
 
     def setFirstTID(self, tid):
         first_tid = self._first_tid
-        if first_tid is None or first_tid > tid:
+        if tid is not None and (first_tid is None or first_tid > tid):
             self._first_tid = tid
 
     def getFirstTID(self):

neo/storage/database/manager.py

@@ -767,12 +767,17 @@ class DatabaseManager(object):
     @requires(_getFirstTID)
     def getFirstTID(self):
         """Return tud of first transaction
-
-        tids are in unpacked format.
         """
         x = self._readable_set
         if x:
-            return min(self._getFirstTID(x) for x in x)
+            getFirstTID = self._getFirstTID
+            min_tid = None
+            for partition in x:
+                tid = getFirstTID(partition)
+                if tid is not None and (min_tid is None or tid < min_tid):
+                    min_tid = tid
+            if min_tid is not None:
+                return util.p64(min_tid)
 
     def _getLastTID(self, partition, max_tid=None):
         """Return tid of last transaction <= 'max_tid' in given 'partition'

neo/storage/handlers/initialization.py

@@ -55,7 +55,7 @@ class InitializationHandler(BaseMasterHandler):
             if packed:
                 self.app.completed_pack_id = pack_id = min(packed.itervalues())
                 conn.send(Packets.NotifyPackCompleted(pack_id))
-        last_tid, last_oid = dm.getLastIDs()
+        last_tid, last_oid = dm.getLastIDs() # PY3
         conn.answer(Packets.AnswerLastIDs(last_tid, last_oid, dm.getFirstTID()))
 
     def askPartitionTable(self, conn):

neo/tests/storage/testStorageDBTests.py

@@ -200,7 +200,7 @@ class StorageDBTests(NeoUnitTestBase):
                 ([oid2], 'user', 'desc', 'ext', False, p64(2), None))
             self.assertEqual(self.db.getTransaction(tid1, False), None)
             self.assertEqual(self.db.getTransaction(tid2, False), None)
-        self.assertEqual(self.db.getFirstTID(), u64(tid1))
+        self.assertEqual(self.db.getFirstTID(), tid1)
         self.assertEqual(self.db.getTransaction(tid1, True),
             ([oid1], 'user', 'desc', 'ext', False, p64(1), None))
         self.assertEqual(self.db.getTransaction(tid2, True),