Fix some flake8 errors (PyMySQL#410)

Author: methane

MySQLdb/connections.py

@@ -5,10 +5,9 @@
 override Connection.default_cursor with a non-standard Cursor class.
 """
 import re
-import sys
 
-from MySQLdb import cursors, _mysql
-from MySQLdb._exceptions import (
+from . import cursors, _mysql
+from ._exceptions import (
     Warning, Error, InterfaceError, DataError,
     DatabaseError, OperationalError, IntegrityError, InternalError,
     NotSupportedError, ProgrammingError,

MySQLdb/cursors.py

@@ -3,14 +3,9 @@
 This module implements Cursors of various types for MySQLdb. By
 default, MySQLdb uses the Cursor class.
 """
-from functools import partial
 import re
-import sys
 
-from ._exceptions import (
-    Warning, Error, InterfaceError, DataError,
-    DatabaseError, OperationalError, IntegrityError, InternalError,
-    NotSupportedError, ProgrammingError)
+from ._exceptions import ProgrammingError
 
 
 #: Regular expression for :meth:`Cursor.executemany`.