[gcc r12-4993] Fix 'contrib/update-copyright.py': 'TypeError: exceptions must derive from BaseException'

[Thomas Schwinge <tschwinge@gcc.gnu.org>]

https://gcc.gnu.org/g:eb4a3e6a9a894238580a8209f59008d375809b2b

commit r12-4993-geb4a3e6a9a894238580a8209f59008d375809b2b
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Fri Oct 22 15:54:42 2021 +0200

    Fix 'contrib/update-copyright.py': 'TypeError: exceptions must derive from BaseException'
    
    Running 'contrib/update-copyright.py' currently fails:
    
        [...]
        Traceback (most recent call last):
          File "contrib/update-copyright.py", line 365, in update_copyright
            canon_form = self.canonicalise_years (dir, filename, filter, years)
          File "contrib/update-copyright.py", line 270, in canonicalise_years
            (min_year, max_year) = self.year_range (years)
          File "contrib/update-copyright.py", line 253, in year_range
            year_list = [self.parse_year (year)
          File "contrib/update-copyright.py", line 253, in <listcomp>
            year_list = [self.parse_year (year)
          File "contrib/update-copyright.py", line 250, in parse_year
            raise self.BadYear (string)
        TypeError: exceptions must derive from BaseException
    
        During handling of the above exception, another exception occurred:
    
        Traceback (most recent call last):
          File "contrib/update-copyright.py", line 796, in <module>
            GCCCmdLine().main()
          File "contrib/update-copyright.py", line 527, in main
            self.copyright.process_tree (dir, filter)
          File "contrib/update-copyright.py", line 458, in process_tree
            self.process_file (dir, filename, filter)
          File "contrib/update-copyright.py", line 421, in process_file
            res = self.update_copyright (dir, filename, filter,
          File "contrib/update-copyright.py", line 366, in update_copyright
            except self.BadYear as e:
        TypeError: catching classes that do not inherit from BaseException is not allowed
    
    Fix up for commit 3b25e83536bcd1b2977659a2c6d9f0f9bf2a3152
    "Port update-copyright.py to Python3".
    
            contrib/
            * update-copyright.py (class BadYear): Derive from 'Exception'.

Diff:
---
 contrib/update-copyright.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/contrib/update-copyright.py b/contrib/update-copyright.py
index 2b2bb11d2e6..d13b963a147 100755
--- a/contrib/update-copyright.py
+++ b/contrib/update-copyright.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2013-2020 Free Software Foundation, Inc.
+# Copyright (C) 2013-2021 Free Software Foundation, Inc.
 #
 # This script is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -233,7 +233,7 @@ class Copyright:
     def add_external_author (self, holder):
         self.holders[holder] = None
 
-    class BadYear():
+    class BadYear (Exception):
         def __init__ (self, year):
             self.year = year