[Rpm-metadata] Zero epoch vs no epoch (patch)

[seth vidal]

On Sat, 2006-04-29 at 13:32 -0700, Panu Matilainen wrote:
> On Sat, 29 Apr 2006, Christoph Thiel wrote:
> 
> > On Sat, 29 Apr 2006, Panu Matilainen wrote:
> >
> >>>>  - Even if no epoch is specified, the metadata still specifies this
> >>>>    as "0".  For most code paths this is no problem as for all
> >>>>    comparisons of version data, a missing epoch is the same as a "0"
> >>>>    epoch. This should not be a huge problem and would be only a
> >>>>    cleanup item for the repodata.
> >>>
> >>> what does removing 0-epoch items buy us?
> >>
> >> What it buys is support for ancient rpm versions. Remember those
> >> monstrosities where non-existing epoch is not equal to zero epoch, epoch
> >> promotion and all that fun? I couldn't personally care less about the
> >> old rpm versions but there are people who do care, for example Dag and
> >> Matthias:
> >> http://lists.freshrpms.net/pipermail/freshrpms-list/2006-April/014022.html
> >>
> >> Removing those zero epochs from repodata makes yum rather unhappy, dunno
> >> about smart, so changing the default is not really a possibility. But
> >> then neither supports the prehistoric versions that are of concern here.
> >> Attached quick hack of a patch adds a switch to turn off adding those
> >> artificial zero epochs, using this as necessary this should be enough to
> >> allow using repodata with full rpm 3.0.x - 4.4.x range.
> >
> > When we were implementing rpm-md support for our online update channels,
> > we stumbled over the epoch thingy as well, but had to add the epoch="0",
> > to keep yum & smart intact. The funny thing we found was the fact that rpm
> > itself doesn't handel an empty epoch consistently -- if there is any
> > interest, I'll dig into the rpm code again to give you the details...
> 
> IIRC rpm 4.2.1 was the first version of rpm to handle zero vs no epoch 
> equally and sanely, except for a bug in "freshen" case where it did matter 
> for rpm itself until recently (fixed last year or so). Other than the 
> freshen issue (which didn't affect depsolvers) I'm not aware of any 
> *recent* issues wrt epochs. Before rpm 4.2.1 there was the promote-epoch 
> behavior on by default and whatnot.. a horrid mess especially thinking 
> about it afterwards :)
> 

Why do you need this? What system isn't using a modern version of rpm?

-sv