Fixes

| Traceback (most recent call last):
|   File "/usr/bin/smart", line 194, in ?
|     main(sys.argv[1:])
|   File "/usr/bin/smart", line 167, in main
|     exitcode = iface.run(opts.command, opts.argv)
|   File "/usr/lib/python2.4/site-packages/smart/interface.py", line 53, in run
|     result = _command.main(self._ctrl, opts)
|   File "/usr/lib/python2.4/site-packages/smart/commands/query.py", line 283,
in main
|     if pattern.search(info.getDescription()):
| TypeError: expected string or buffer

which happens when a package has an empty %description. Ditto for summary.