Reduce try..except nesting.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@1823 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/storage/database/mysqldb.py

@@ -264,6 +264,8 @@ class MySQLDatabaseManager(DatabaseManager):
                     % (oid, before_tid))
             try:
                 serial, compression, checksum, data = r[0]
+            except IndexError:
+                return None
             r = q("""SELECT serial FROM obj
                         WHERE oid = %d AND serial >= %d
                         ORDER BY serial LIMIT 1""" \
@@ -272,8 +274,6 @@ class MySQLDatabaseManager(DatabaseManager):
                 next_serial = r[0][0]
             except IndexError:
                 next_serial = None
-            except IndexError:
-                return None
         else:
             # XXX I want to express "HAVING serial = MAX(serial)", but
             # MySQL does not use an index for a HAVING clause!