[CI] Use constant commit sha (facebook#20828)

When running the publish workflow, either via the command line or
via the daily cron job, we should use a constant SHA instead of
whatever happens to be at the head of the main branch at the time the
workflow is run.

The difference is subtle: currently, the SHA is read at runtime,
each time the workflow is run. With this change, the SHA is read right
before the workflow is created and passed in as a constant parameter.

In practical terms, this means if a workflow is re-run via the CircleCI
web UI, it will always re-run using the same commit SHA as the original
workflow, instead of fetching the latest SHA from GitHub, which may
have changed.

Also avoids a race condition where the head SHA changes in between the
Next publish job and the Experimental publish job.

.circleci/config.yml

@@ -579,7 +579,7 @@ workflows:
           name: Publish to Next channel
           requires:
             - setup
-          commit_sha: master
+          commit_sha: << pipeline.git.revision >>
           release_channel: stable
           dist_tag: next
       - publish_prerelease:
@@ -590,7 +590,7 @@ workflows:
             # different versions of the same package, even if they use different
             # dist tags.
             - Publish to Next channel
-          commit_sha: master
+          commit_sha: << pipeline.git.revision >>
           release_channel: experimental
           dist_tag: experimental
 

scripts/release/publish-using-ci-workflow.js

@@ -77,14 +77,19 @@ async function pollUntilWorkflowFinishes(workflowID) {
 }
 
 async function main() {
+  const headCommitResponse = await fetch(
+    'https://api.github.com/repos/facebook/react/commits/master'
+  );
+  const headCommitJSON = await headCommitResponse.json();
+  const headCommitSha = headCommitJSON.sha;
+
   const pipelineResponse = await fetch(
     'https://circleci.com/api/v2/project/github/facebook/react/pipeline',
     {
       method: 'post',
       body: JSON.stringify({
         parameters: {
-          // TODO: Make commit SHA configurable
-          prerelease_commit_sha: 'master',
+          prerelease_commit_sha: headCommitSha,
         },
       }),
       headers: {