python-dateutil will be updated to version 2.x and there may be changes that affect this package. If python-rhsm will work with the newer python-dateutil, you can safely close this bug. If python-rhsm really does require python-dateutil 1.5, please use Requires: python-dateutil15 for Fedora versions of the package until it can be updated.
rhsm only does a simple dateutil.parse.parse(utc_time_string) call. It should be fine with any version of dateutil.