Allow mutable tags

[julienrbrt]

We are using buf for the cosmos/cosmos-sdk, and lately, we are encountering missing commits. This breaks our need of proto versioning and our upgrade documentation (e.g., https://github.com/cosmos/cosmos-sdk/blob/main/UPGRADING.md#protobuf-1)

Failure: buf.build/cosmos/cosmos-sdk:106f3380b73b4157a9e0149cbd30bf9f: does not exist
Failure: buf.build/cosmos/cosmos-sdk:af8d763f189a4482b59f9f283b446293: does not exist.

AFAIK, commits are immutable, and we can find it in the commit history: https://buf.build/cosmos/cosmos-sdk/commits/af8d763f189a4482b59f9f283b446293 but without content. Only the recent commits are available.

[robbertvanginkel]

While commits are indeed immutable on the BSR, the repository in which they exist can be deleted. It looks like cosmos-sdk has a dependency on buf.build/googleapis/googleapis, which was recently deleted and re-created (please see #1380 for more context on that).

Unfortunately, the error message that is propagated to the cli and website aren't clear about this and make it seem like it is a problem with the cosmos module rather than one of its dependencies. We're currently working on getting more descriptive errors into the cli and the website. I'll leave this open till we improve that, but for the root cause or any other comments on how the googleapis recreation has impacted I'll ask that we centralize that discussion in #1380.

[julienrbrt]

That's unfortunate…
Say I need a buf commit linked to a tag, but because the commit content is deleted, I cannot access it. Am I able to push another commit with the same tag (I don't think so, but maybe I am missing something)?

[robbertvanginkel]

Tags cannot be deleted today, #765 tracks some work related to changing that but I have nothing concrete to share there yet.

[bufdev]

We're going to potentially be making changes to tags to allow this in the near future. Will keep this issue open as we update you on that.

[doriable]

Tags are now labels, and labels are mutable: https://buf.build/docs/concepts/commits-labels#labels
Going to close this for now, feel free to re-open if there are any questions or concerns.

[julienrbrt]

This is perfect, thank you!