Fix npm latest tag issue when releasing patches (#32543)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/32543

Changelog: [Internal] Fix npm `latest` tag issue that occurs when we release a patch on an older minor version

Context:
* There are two types of tags, git and npm, they are unrelated.

* When we publish a stable release, we set the git tag `latest`. This logic is faulty when we release a patch to an older version.

* When publishing a package to npm, if you don't provide an explicit tag, the `latest` tag will be applied -- at least that's how I've understood the [docs here](https://docs.npmjs.com/cli/v7/commands/npm-dist-tag#description). This again is faulty logic when we release a patch to an older version.

* npm and git's `latest` tag should always point to our most recent stable version

This change:
* Introduces a `--latest` flag for `bump-oss-script` that will indicate that the release we're running (either a stable or pre-release) should really be considered "latest"
* If the version is not a pre-release and the `--latest` flag is set, we will set the git `latest` tag
* Later, in the circleCI job that we use to publish the npm package, we will see if the current commit is git-tagged as `latest`. If it is, then we'll explicitly tell npm to use `latest` tag but most importantly, if it's not, we'll set a tag of the form `{major}.{minor}-stable`.
* This type of tag (ex. `0.66-stable`) is new and the intention is that it will always point to latest of that minor version.

Reviewed By: hramos

Differential Revision: D32196239

fbshipit-source-id: 4c881851eebcad8585732ff0c07322413ac46ce5

scripts/bump-oss-version.js

@@ -34,6 +34,11 @@ let argv = yargs
   .option('v', {
     alias: 'to-version',
     type: 'string',
+  })
+  .option('l', {
+    alias: 'latest',
+    type: 'boolean',
+    default: false,
   }).argv;
 
 const nightlyBuild = argv.nightly;
@@ -221,8 +226,9 @@ if (!nightlyBuild) {
   let remote = argv.remote;
   exec(`git push ${remote} v${version}`);
 
-  // Tag latest if doing stable release
-  if (prerelease == null) {
+  // Tag latest if doing stable release.
+  // This will also tag npm release as `latest`
+  if (prerelease == null && argv.latest) {
     exec('git tag -d latest');
     exec(`git push ${remote} :latest`);
     exec('git tag latest');

scripts/publish-npm.js

@@ -87,9 +87,11 @@ const rawVersion =
       buildTag;
 
 let version,
+  major,
+  minor,
   prerelease = null;
 try {
-  ({version, prerelease} = parseVersion(rawVersion));
+  ({version, major, minor, prerelease} = parseVersion(rawVersion));
 } catch (e) {
   echo(e.message);
   exit(1);
@@ -155,12 +157,24 @@ if (dryRunBuild) {
   exit(0);
 }
 
+// Running to see if this commit has been git tagged as `latest`
+const latestCommit = exec("git rev-list -n 1 'latest'", {
+  silent: true,
+}).stdout.replace('\n', '');
+const isLatest = currentCommit === latestCommit;
+
+const releaseBranch = `${major}.${minor}-stable`;
+
 // Set the right tag for nightly and prerelease builds
+// If a release is not git-tagged as `latest` we use `releaseBranch` to prevent
+// npm from overriding the current `latest` version tag, which it will do if no tag is set.
 const tagFlag = nightlyBuild
   ? '--tag nightly'
   : prerelease != null
   ? '--tag next'
-  : '';
+  : isLatest
+  ? '--tag latest'
+  : `--tag ${releaseBranch}`;
 
 // use otp from envvars if available
 const otpFlag = otp ? `--otp ${otp}` : '';