python-dateutil will be updated to version 2.x and there may be changes that affect this package. If s3cmd will work with the newer python-dateutil, you can safely close this bug. If s3cmd really does require python-dateutil 1.5, please use Requires: python-dateutil15 for Fedora versions of the package until it can be updated.
this is using dateutil.parser.parse() only, which should be safe. I don't think we've encountered any packages with this Change that were impacted by a new parser module.
1.5.2.1-5 is in F20 & 21 now, and EPEL 6 and 7 as soon as their schedule permits pushing. All will have this fix.