py3: do not use "except Exception, e:" syntax

If catching the exception is done with "except Exception as e:" this
will work only from 2.6. To maintain backward compatibility with 2.4 I
have used sys.exc_info(). A bit of a wart, but it works.

smem

@@ -725,7 +725,8 @@ try:
         showsystem()
     else:
         showpids()
-except IOError, e:
+except IOError:
+    _, e, _ = sys.exc_info()
     if e.errno == errno.EPIPE:
         pass
 except KeyboardInterrupt: