[packagekit] Cache clean

[David Timms]

Richard Hughes wrote:
> On Sun, 2008-04-13 at 09:46 -0700, mirttex85-pk at yahoo.com.br wrote:
>> why not schedule this regulary by packagekit as we have with the
>> update lists of packages?
> 
> Can't we just nuke the downloaded cache when we do RefreshCache?
Something to think about: {not sure of the terminology though}.

It might be worth moving the download cache aside, trying to refresh, 
and if that fails to complete, then move the cache back, so that the 
various commands can still run based on the most recently retrieved 
complete info.

I say this in reference to say yum on fedora where it is somewhat common 
to see the metadata indicator file be out of sync with currently 
retrievable metadata. This leads to attempts to retrieve the matching 
file from the whole list of available mirrors, failing because it was 
really the indicator file that was not in sync. For a fail situation 
like this having legit but slightly old metadata is better than not 
being able to use it at all. I'm not sure if that is an issue for other 
underlying package managers.