allow reusing existing tag as long as it points to the correct commit

Author: aduh95

lib/promote_release.js

@@ -334,13 +334,27 @@ export default class ReleasePromotion extends Session {
 
     const releaseInfo = isLTS ? `${ltsCodename} (LTS)` : '(Current)';
 
-    await new Promise((resolve, reject) => {
-      const api = new gst.API(process.cwd());
-      api.sign(`v${version}`, releaseCommitSha, {
-        insecure: false,
-        m: `${this.date} Node.js v${version} ${releaseInfo} Release`
-      }, (err) => err ? reject(err) : resolve());
-    });
+    try {
+      await new Promise((resolve, reject) => {
+        const api = new gst.API(process.cwd());
+        api.sign(`v${version}`, releaseCommitSha, {
+          insecure: false,
+          m: `${this.date} Node.js v${version} ${releaseInfo} Release`
+        }, (err) => err ? reject(err) : resolve());
+      });
+    } catch (err) {
+      const tagCommitSHA = await forceRunAsync('git', [
+        'rev-parse', `refs/tags/v${version}^0`
+      ], { captureStdout: true, ignoreFailure: false });
+      if (tagCommitSHA.trim() !== releaseCommitSha) {
+        throw new Error(
+          `Existing version tag points to ${tagCommitSHA.trim()} instead of ${releaseCommitSha}`,
+          { cause: err }
+        );
+      }
+      await forceRunAsync('git', ['tag', '--verify', `v${version}`], { ignoreFailure: false });
+      this.cli.info('Using the existing tag');
+    }
   }
 
   // Set up the branch so that nightly builds are produced with the next