Allow removed collection information from previous major releases

[felixfontein]

This allows to improve ansible-community/antsibull-docs#341 to also create stubs for collections removed in older major Ansible releases.

[felixfontein]

How the data could look like: ansible-community/ansible-build-data#465

[gotmax23]

We should probably have a policy re. how long we keep these tombstones around. Also, would it make sense to read removed_collections from previous releases instead?

[felixfontein]

We should probably have a policy re. how long we keep these tombstones around.

True. Right now I'd say "until we decide we have to clean up", since that data doesn't take up much space. But in 10 years or so some cleanup might not hurt :)

Also, would it make sense to read removed_collections from previous releases instead?

To avoid having to read data from more than one directory in ansible-build-data. At some point I'd like every Ansible release's sdist to contain all metadata needed to rebuild itself, so you don't have to clone a specific tag of the ansible-build-data repo. For that to be feasible only the contents (resp. a subset of them) of one directory in ansible-build-data should be included.

[gotmax23]

We should probably have a policy re. how long we keep these tombstones around.

True. Right now I'd say "until we decide we have to clean up", since that data doesn't take up much space. But in 10 years or so some cleanup might not hurt :)

I think we should at least have some set amount of time and potentially print a warning message if the removed_collections entries are too old. Maybe ask the SC or DAWGs for their opinions about how long to keep the tombstones around?

Also, would it make sense to read removed_collections from previous releases instead?

To avoid having to read data from more than one directory in ansible-build-data.

Fair enough. I guess if we're just cping the collection-meta file from one directory to another during the new major release process, it's not a big deal to keep removed_collections entries from the previous release.

[felixfontein]

@gotmax23 thanks for reviewing this!