`Pkg.add` no longer works with SHAs from PRs

[MilesCranmer]

I think the change in #2330:

- const refspecs = ["+refs/*:refs/remotes/cache/*"]
+ const refspecs = ["+refs/heads/*:refs/remotes/cache/heads/*"]

Is causing the following issue in AirspeedVelocity.jl: MilesCranmer/AirspeedVelocity.jl#113. I am still diagnosing this but I just wanted to post it to see if anybody had suggestions for a quick fix.

I guess the solution might be on my side, to change the URL, rather than rely on a cross-repository revision lookup? Edit: Well I guess this is just two remotes, so git should handle it?

[MilesCranmer]

Ugh. Actually it seems like requiring a different repository URL to compare PR with master is going to be a pain and a half to implement. Much easier before when it was just comparing two revisions like git. Is there any way I can manually specify the refspecs? Or any way to make Julia aware of both Git remotes? @KristofferC @IanButterworth

[MilesCranmer]

In the PR I see that @DilumAluthge made this suggestion at one point -

I think that in addition to refs/heads/*, you'll also need refs/remotes/* or something like that?

Do you think this would this fix it?

[MilesCranmer]

Copying from #2330:

@MilesCranmer: Will do that for now. Can the change be reverted? It seems it fundamentally alters the behavior of Pkg.add. I understand there's this speedup, but that seems to only be because it removes some functionality, not that it's more efficient.

I think it would be better to have a special keyword for this rather than changing the standard behavior, perhaps heads=false by default, and heads=true to enable this reduced refspec

@KristofferC: Can you elaborate the exact situation that causes this to happen? It doesn't be wide spread so what is the unique thing about this situation?

It is seen when installing a specific revision from a PR, when that PR's commit is based in a fork of the repository. For example: there is a PR to my repository MilesCranmer/SymbolicRegression.jl#515 from a fork. One of the commits in this PR is f154755ba9b06bd1bb6251b4172d015fbade5e22.

On Julia 1.12, it fails to get the commit:

julia> ]add https://github.com/MilesCranmer/SymbolicRegression.jl#f154755ba9b06bd1bb6251b4172d015fbade5e22
    Updating git-repo `https://github.com/MilesCranmer/SymbolicRegression.jl`
ERROR: Did not find rev f154755ba9b06bd1bb6251b4172d015fbade5e22 in repository

This is because the query used by Pkg.add no longer picks up that commit SHA.

However, on every previous version of Julia, the command would work fine:

julia> ]add https://github.com/MilesCranmer/SymbolicRegression.jl#f154755ba9b06bd1bb6251b4172d015fbade5e22
    Updating git-repo `https://github.com/MilesCranmer/SymbolicRegression.jl`
    Updating registry at `~/.julia/registries/General.toml`
   Resolving package versions...
    Updating `/private/var/folders/1h/xyppkvx52cl6w3_h8bw_gdqh0000gr/T/tmp.VWD3Drij0O/Project.toml`
  [8254be44] + SymbolicRegression v2.0.0-alpha.8 `https://github.com/MilesCranmer/SymbolicRegression.jl#f154755`
    Updating `/private/var/folders/1h/xyppkvx52cl6w3_h8bw_gdqh0000gr/T/tmp.VWD3Drij0O/Manifest.toml`

#= ... =#

julia> versioninfo()
Julia Version 1.11.7
Commit f2b3dbda30a (2025-09-08 12:10 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: macOS (arm64-apple-darwin24.0.0)
  CPU: 8 × Apple M1 Pro
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, apple-m1)
Threads: 6 default, 0 interactive, 3 GC (on 6 virtual cores)

This clones the repository at the specific revision in the PR.

Now, there are a couple subtleties, which might be why it hasn't been widely reported yet. If you have already resolved the refs and have that repository (with the PR refs) in your Julia cache, this error will not trigger. This is why I saw it first in CI rather than locally. If I had ran the Julia 1.11, and not cleared my registry cache, and ran the Julia 1.12 command, it would actually succeed!

I think I first saw this with AirspeedVelocity.jl since it (1) has a fresh Julia cache, and (2) uses Pkg.add directly to install the PR version, rather than github checkout. The github checkout action uses the full refspec so it still works. But Pkg.add no longer does.

[KristofferC]

#4441 then maybe. Can you try it?

[MilesCranmer]

Cool! It works