up2date-2.9.3-1.2.1AS and rhn_register-2.9.3-1.2.1AS barf if proxy user or proxy password in the config file are entirely numeric. I suppose we could use the default or previous value to tell whether the value is to be converted to int or remain as a string. E.g., if the key is already defined, with a value that is an integer, we convert the new value to integer. If it is already defined to a string, we leave the new value alone. Otherwise, we may apply the current heuristics, just to make sure we're not unexpectedly changing behavior.
Since Enterprise Linux 2.1 has gone into maintenance mode, this bug will not be fixed in 2.1. This though has been fixed in Enterprise Linux 3 and 4 - see bugs: 145554 159856 Regards, Clifford.