CI builds fail with "does master exist?"

Affected Packages

@changesets/cli @changesets/git

Problem

It seems that 2.13.0 of @changesets/cli broke our CI builds. (I’m assuming that’s because of the update to @changesets/git.) We now get this when running changeset status on PRs:

🦋  error Error: Failed to find where HEAD diverged from master. Does master exist?
🦋  error     at getDivergedCommit (/opt/hostedtoolcache/node/12.20.1/x64/lib/node_modules/@changesets/cli/node_modules/@changesets/git/dist/git.cjs.dev.js:58:11)
🦋  error     at async getChangedFilesSince (/opt/hostedtoolcache/node/12.20.1/x64/lib/node_modules/@changesets/cli/node_modules/@changesets/git/dist/git.cjs.dev.js:169:22)
🦋  error     at async Object.getChangedPackagesSinceRef (/opt/hostedtoolcache/node/12.20.1/x64/lib/node_modules/@changesets/cli/node_modules/@changesets/git/dist/git.cjs.dev.js:208:24)
🦋  error     at async getStatus (/opt/hostedtoolcache/node/12.20.1/x64/lib/node_modules/@changesets/cli/dist/cli.cjs.dev.js:953:27)
🦋  error     at async run$1 (/opt/hostedtoolcache/node/12.20.1/x64/lib/node_modules/@changesets/cli/dist/cli.cjs.dev.js:1197:11)

We’re running this on Ubuntu machines (“latest” version) in Azure Pipelines. Couldn’t reproduce the problem locally.

Confirmed that installing @changesets/cli version 2.12.0 fixed the problem.

Proposed solution

🤷‍♂️ No clue. Let me know if there is other info I can provide to help debug. Thanks!

[steve-taylor]

For those of you struggling with this in GitHub Actions workflows triggered by pull requests, here’s what works for me:

1. Check out the branch rather than the result of merging main into your branch. Also get the full commit history.

   uses: actions/checkout@v3
   with:
     ref: ${{github.event.pull_request.head.sha}}
     fetch-depth: 0
   

2. The workflow runner hasn’t checked out main locally, so refer to it as origin/main in the changeset status command.

   run: npx changeset status --since origin/main
   

[will-stone]

For anyone struggling with this in GitLab, I ended up using this in my job:

  script:
    # Required so that Changesets can compare with main branch
    - git config --global --add safe.directory /builds/path/to/project-name
    - git pull -f origin main:main
    - npx changeset status

Please let me know if there’s any major downsides to this approach that I am not aware of 😬