Fixed a spurious test failure due to an change in an exception's

string representation.

src/ZODB/tests/testConnectionSavepoint.txt

@@ -182,15 +182,15 @@ However, using a savepoint invalidates any savepoints that come after it:
     >>> root['bob-balance']
     100.0
 
-    >>> savepoint2.rollback()
+    >>> savepoint2.rollback() # doctest: +ELLIPSIS
     Traceback (most recent call last):
     ...
-    InvalidSavepointRollbackError
+    InvalidSavepointRollbackError...
 
-    >>> savepoint1.rollback()
+    >>> savepoint1.rollback() # doctest: +ELLIPSIS
     Traceback (most recent call last):
     ...
-    InvalidSavepointRollbackError
+    InvalidSavepointRollbackError...
 
     >>> transaction.abort()