Fix flake errors after moving to python 3

luigi/contrib/docker_runner.py

@@ -236,7 +236,7 @@ def run(self):
             self.__logger.error("Container " + container_name +
                                 " exited with non zero code: " + message)
             raise
-        except ImageNotFound as e:
+        except ImageNotFound:
             self.__logger.error("Image " + self._image + " not found")
             raise
         except APIError as e:

luigi/contrib/ftp.py

@@ -213,7 +213,7 @@ def _rm_recursive(self, ftp, path):
 
         try:
             names = ftp.nlst()
-        except ftplib.all_errors as e:
+        except ftplib.all_errors:
             # some FTP servers complain when you try and list non-existent paths
             return
 
@@ -226,7 +226,7 @@ def _rm_recursive(self, ftp, path):
                 ftp.cwd(wd)   # don't try a nuke a folder we're in
                 ftp.cwd(path)  # then go back to where we were
                 self._rm_recursive(ftp, name)
-            except ftplib.all_errors as e:
+            except ftplib.all_errors:
                 ftp.delete(name)
 
         try:

luigi/contrib/mssqldb.py

@@ -23,7 +23,7 @@
 
 try:
     import _mssql
-except ImportError as e:
+except ImportError:
     logger.warning("Loading MSSQL module without the python package pymssql. \
         This will crash at runtime if SQL Server functionality is used.")
 

luigi/contrib/mysqldb.py

@@ -26,7 +26,7 @@
 try:
     import mysql.connector
     from mysql.connector import errorcode, Error
-except ImportError as e:
+except ImportError:
     logger.warning("Loading MySQL module without the python package mysql-connector-python. \
        This will crash at runtime if MySQL functionality is used.")
 

luigi/lock.py

@@ -142,7 +142,7 @@ def _read_pids_file(pid_file):
     # First setup a python 2 vs 3 compatibility
     # http://stackoverflow.com/a/21368622/621449
     try:
-        FileNotFoundError
+        FileNotFoundError  # noqa: F823
     except NameError:
         # Should only happen on python 2
         FileNotFoundError = IOError

tox.ini

@@ -97,6 +97,7 @@ commands =
 # By putting it here, local flake8 runs will also pick it up.
 [flake8]
 max-line-length=160
+builtins = unicode
 
 [testenv:flake8]
 deps =