/plugin install fails with shallow clone when ref is fully-qualified (refs/tags/<tag>)

[dfrysinger]

Summary

/plugin install <plugin>@<marketplace> fails to fetch any plugin whose marketplace entry points at a tagged release, because the installer passes a fully-qualified ref to git clone --depth 1 --branch, which git rejects.

Repro

/plugin install pm-skills@awesome-copilot

Observed

✗ Failed to install plugin: Failed to fetch GitHub plugin Avyayalaya/pm-skills-arsenal:
Error: Command failed: git clone --depth 1 --progress --branch refs/tags/v2.1.0 \
  https://github.com/Avyayalaya/pm-skills-arsenal.git \
  /Users/<user>/Library/Caches/copilot/marketplaces/Avyayalaya--pm-skills-arsenal
fatal: Remote branch refs/tags/v2.1.0 not found in upstream origin

The tag exists — git ls-remote --tags https://github.com/Avyayalaya/pm-skills-arsenal.git shows refs/tags/v2.1.0.

Root cause

git clone --depth 1 --branch <ref> requires a short ref name (e.g. v2.1.0), not a fully-qualified one (refs/tags/v2.1.0). The shallow upload-pack protocol only advertises short names to --branch.

Reproduction:

# fails
git clone --depth 1 --branch refs/tags/v2.1.0 https://github.com/Avyayalaya/pm-skills-arsenal.git
# fatal: Remote branch refs/tags/v2.1.0 not found in upstream origin

# succeeds
git clone --depth 1 --branch v2.1.0 https://github.com/Avyayalaya/pm-skills-arsenal.git

Suggested fix

Strip the refs/tags/ (and refs/heads/) prefix before passing the value to --branch, or omit --depth 1 when a fully-qualified ref is needed.

Affected version

GitHub Copilot CLI 1.0.51-2

Environment

• OS: macOS (Darwin, arm64)
• git: system default

[dfrysinger]

Related: filed a complementary issue against the source marketplace where this surfaced: github/awesome-copilot#1783. That issue tracks correcting the specific bad entry. Leaving this issue open as I think the CLI-side fix (normalize/strip fully-qualified ref prefixes, or omit --depth 1 for fully-qualified refs) is the more general and durable fix.

[dfrysinger]

Oops thanks! Tried to look but didnt find that. Looks like we can close this.