Don't use repr(tid) to get a serial.

repr() must return text, and we need bytes.

src/ZODB/BaseStorage.py

@@ -98,7 +98,7 @@ class BaseStorage(UndoLogCompatible):
 
         t = time.time()
         t = self._ts = TimeStamp(*(time.gmtime(t)[:5] + (t%60,)))
-        self._tid = repr(t)
+        self._tid = t.raw()
 
         # ._oid is the highest oid in use (0 is always in use -- it's
         # a reserved oid for the root object).  Our new_oid() method
@@ -247,7 +247,7 @@ class BaseStorage(UndoLogCompatible):
                 now = time.time()
                 t = TimeStamp(*(time.gmtime(now)[:5] + (now % 60,)))
                 self._ts = t = t.laterThan(self._ts)
-                self._tid = repr(t)
+                self._tid = t.raw()
             else:
                 self._ts = TimeStamp(tid)
                 self._tid = tid

src/ZODB/utils.py

@@ -117,7 +117,7 @@ def newTid(old):
     ts = TimeStamp(*time.gmtime(t)[:5]+(t%60,))
     if old is not None:
         ts = ts.laterThan(TimeStamp(old))
-    return `ts`
+    return ts.raw()
 
 
 def oid_repr(oid):