Fix linting issues

This patch fixes some minor linting issues that pylint doesn't catch.

Change-Id: Ibab3b8cbce1938787d74b11e901d2717bd169c42

Author: nmariz

lib/mysql/connector/__init__.py

@@ -70,7 +70,6 @@
     Warning,
     custom_error_exception,
 )
-from .optionfiles import read_option_files
 from .pooling import connect
 
 Connect = connect
@@ -97,6 +96,7 @@
     "NotSupportedError",
     "DataError",
     "IntegrityError",
+    "PoolError",
     "ProgrammingError",
     "OperationalError",
     "InternalError",

lib/mysql/connector/network.py

@@ -32,7 +32,6 @@
 import os
 import socket
 import struct
-import sys
 import zlib
 
 from collections import deque
@@ -278,43 +277,7 @@ def recv_plain(self):
                 errno=2055, values=(self.get_address(), _strioerror(err))
             ) from err
 
-    def recv_py26_plain(self):
-        """Receive packets from the MySQL server"""
-        try:
-            # Read the header of the MySQL packet, 4 bytes
-            header = bytearray(b"")
-            header_len = 0
-            while header_len < 4:
-                chunk = self.sock.recv(4 - header_len)
-                if not chunk:
-                    raise InterfaceError(errno=2013)
-                header += chunk
-                header_len = len(header)
-
-            # Save the packet number and payload length
-            self._packet_number = header[3]
-            payload_len = struct.unpack("<I", header[0:3] + b"\x00")[0]
-
-            # Read the payload
-            rest = payload_len
-            payload = init_bytearray(b"")
-            while rest > 0:
-                chunk = self.sock.recv(rest)
-                if not chunk:
-                    raise InterfaceError(errno=2013)
-                payload += chunk
-                rest = payload_len - len(payload)
-            return header + payload
-        except IOError as err:
-            raise OperationalError(
-                errno=2055, values=(self.get_address(), _strioerror(err))
-            ) from err
-
-    if sys.version_info[0:2] == (2, 6):
-        recv = recv_py26_plain
-        recv_plain = recv_py26_plain
-    else:
-        recv = recv_plain
+    recv = recv_plain
 
     def _split_zipped_payload(self, packet_bunch):
         """Split compressed payload"""

lib/mysqlx/connection.py

@@ -2723,16 +2723,16 @@ def _validate_settings(settings):
             )
         except (AttributeError, ValueError) as err:
             raise InterfaceError(f"Invalid SSL Mode '{settings['ssl-mode']}'") from err
-        if not "ssl-ca" in settings and settings["ssl-mode"] in [
+        if "ssl-ca" not in settings and settings["ssl-mode"] in [
             SSLMode.VERIFY_IDENTITY,
             SSLMode.VERIFY_CA,
         ]:
             raise InterfaceError("Cannot verify Server without CA")
 
-    if "ssl-crl" in settings and not "ssl-ca" in settings:
+    if "ssl-crl" in settings and "ssl-ca" not in settings:
         raise InterfaceError("CA Certificate not provided")
 
-    if "ssl-key" in settings and not "ssl-cert" in settings:
+    if "ssl-key" in settings and "ssl-cert" not in settings:
         raise InterfaceError("Client Certificate not provided")
 
     if "ssl-ca" in settings and settings.get("ssl-mode") not in [
@@ -2880,7 +2880,7 @@ def _validate_connection_attributes(settings):
             return
         if not (
             conn_attrs.startswith("[") and conn_attrs.endswith("]")
-        ) and not conn_attrs in ["False", "false", "True", "true"]:
+        ) and conn_attrs not in ["False", "false", "True", "true"]:
             raise InterfaceError(
                 "The value of 'connection-attributes' must be a boolean or a "
                 f"list of key-value pairs, found: '{conn_attrs}'"