Dependency rebuild for new versions to be synced downstream

[lachmanfrantisek]

User story: As a package maintainer doing a package rebase, I would like to check if the dependencies of my package can be built so the new update does not cause a FTBFS (=failed-to-build-from-source) for a package depending on my package.

There are various smaller use case variants:

• I would like to rebuild all the packages that has my package set as a build requirement.
• I would like to rebuild all packages I specify.
• I would like to build and install the dependent packages.
• I would like to build, test and install the dependent packages (various variants of test source).

Various 3rd party tools/services can do this:

• OBS has built-in support for dependency rebuilds. (The integration for OBS is being worked on in OBS build support packit#2067)
• Koschei is the very right tool to do this, but does not support ad-hock tests for now (Submit test requests through HTTP POST request fedora-infra/koschei#293).
• There is a MPB (https://gitlab.com/fedora/packager-tools/mass-prebuild) tool written for this.
• Python team has a custom tooling for this (TODO: research and link)
• We can also send batch builds to Copr.

Implementation notes:

• Support this as a new job type and support both upstream and dist-git PRs.
• Do this as a next step when creating a dist-git PR.
• Integrate this into the existing tools (fedora-ci dist-git zuul checks).

Requested by:

• packit/user#17

[lachmanfrantisek]

A related, installation-only functionality is covered by packit/tmt-plans#19

[lachmanfrantisek]

We've been asked about this e.g. when onboarding rubygem-cucumber-cucumber-expressions .

[lachmanfrantisek]

Also, a related issue: packit/packit#2196

[lachmanfrantisek]

Since the main place to have this is in dist-git pull-requests, we are prioritising #2453 for the next quarter. (Result of what will be beneficial for this.)