fix: adjust base branch when prepare --security release (#889)

lib/prepare_release.js

@@ -363,8 +363,14 @@ export default class ReleasePreparation extends Session {
     try {
       runSync('git', ['rev-parse', tagName]);
     } catch {
-      this.cli.startSpinner(`Error parsing git ref ${tagName}, attempting fetching it as a tag`);
-      runSync('git', ['fetch', this.upstream, 'tag', '-n', tagName]);
+      this.cli.error(`Error parsing git ref ${tagName}`);
+      this.cli.startSpinner('Attempting fetching it as a tag\n');
+      try {
+        runSync('git', ['fetch', this.upstream, 'tag', '-n', tagName]);
+      } catch (e) {
+        this.cli.error(`${e.message}\nRun: git remote update`);
+        process.exit(1);
+      }
       this.cli.stopSpinner(`Tag fetched: ${tagName}`);
     }
     try {
@@ -765,7 +771,7 @@ export default class ReleasePreparation extends Session {
   }
 
   async prepareLocalBranch() {
-    const { cli } = this;
+    const { cli, isSecurityRelease } = this;
     if (this.newVersion) {
       // If the CLI asked for a specific version:
       const newVersion = semver.parse(this.newVersion);
@@ -789,11 +795,19 @@ export default class ReleasePreparation extends Session {
     // Otherwise, we need to figure out what's the next version number for the
     // release line of the branch that's currently checked out.
     const currentBranch = this.getCurrentBranch();
-    const match = /^v(\d+)\.x-staging$/.exec(currentBranch);
 
+    // In security releases vN.x branch is the base
+    let regex = /^v(\d+)\.x-staging$/;
+    let targetBranch = 'vN.x-staging';
+    if (isSecurityRelease) {
+      regex = /^v(\d+)\.x$/;
+      targetBranch = 'vN.x';
+    }
+
+    const match = regex.exec(currentBranch);
     if (!match) {
       cli.warn(`Cannot prepare a release from ${currentBranch
-          }. Switch to a staging branch before proceeding.`);
+        }. Switch to a ${targetBranch} branch before proceeding.`);
       return;
     }
     this.stagingBranch = currentBranch;