Convert some old-style string exceptions to class exceptions.
diff --git a/Lib/plat-irix5/torgb.py b/Lib/plat-irix5/torgb.py
index f283063..59e3fbe 100755
--- a/Lib/plat-irix5/torgb.py
+++ b/Lib/plat-irix5/torgb.py
@@ -50,7 +50,8 @@
 uncompress.append('uncompress', '--')
 
 
-error = 'torgb.error' # Exception
+class error(Exception):
+	pass
 
 def torgb(filename):
 	temps = []