Accept "0" as an epoch

[sjoerdsimons]

In Debian an zero epoch is actually valid; e.g. woff-tools actually has a zero epoch (0:2009.10.04-2).

[Conan-Kudo]

It is also a valid Epoch in RPM too.

[mlschroe]

This is about the way libsolv normalizes the epoch-version-release. So stripping a zero epoch is correct. What exactly are you trying to solve?

[andrewshadura]

It is not correct since empty epoch doesn't equal to zero epoch.

[andrewshadura]

To clarify: without this change, when woff-tools is requested in a DoD project as a build dependency, OBS keeps downloading and deleting the package files, never satisfying the dependency (because the version doesn’t match).

[mlschroe]

The reason for this is that libsolv's repo_add_deb() does not normalize the epoch as well. Hmm.

The debian packaging guide says that an empty epoch is the same as a zero epoch, so it somewhat makes sense to normalize. But I'm not a debian expert.

Anyway either perl-BSSolv or libsolv needs to change.

[Conan-Kudo]

The debian packaging guide says that an empty epoch is the same as a zero epoch, so it somewhat makes sense to normalize. But I'm not a debian expert.

This is correct. From a solution solving perspective, both RPM and Debian package management expect this.

[andrewshadura]

Well, it is the same (when versions are compared), but as you pointed out, it’s not the same when it comes to the file name comparison. If you drop it in one place, but then expect it in the file name, you won’t get a match.

[Conan-Kudo]

File names should be fetched by getting the basename from the URL in the repository metadata, not by constructing strings based on NEVRA.

[andrewshadura]

Probably. But apparently that’s not what happens, for whatever reason.

[Conan-Kudo]

That's a bug somewhere in OBS then. :)

[andrewshadura]

Unrelated: I keep misreading your username as Conan-Sudo 😃

[mlschroe]

The filename is not the problem. The OBS repo server fetches the binary correctly, but then a bit later the scheduler does not identify the binary as the evr is different, so it gets deleted again.

[mlschroe]

The repo parsers in the obs-build package also leave the epoch for debian metadata. So I think the easiest way forward is to not normalize and accept the pull request.
It's still somewhat ugly and dangerous that the code in the repo metadata parser must match libsolv's package parser, but I think we have to live with that.

[andrewshadura]

@mlschroe, thanks, I think was misremembering the exact nature of the issue. And thanks for merging.

[mlschroe]

Sorry that this took so long. I somehow missed that you opened this pull request.