Comment 6 for bug 250645

Erasing cached package metadata does not modify what's already stored in Smart's cache, which means, in rpm-md channels for example, if you clear the files, then run 'update', it will re-download repomod.xml, confirm digest hasn't change, and do nothing else. No other packages will get downloaded, thus storage space is spared.

OTOH, for YaST2 channels which do not have md5sum check on the channel metadata, if the download is corrupt, the channel loader will crash, forcing the user to rm the files in <datadir>/channels and run update again. In that situation, clean is handy because it erases the file without the need for the user to know it's location.

And lest, if you want the digest to change if the cached metadata files have been erased, I will have to work a bit more to make that happen.

I hope that answers your questions.