pass in the specified git branch ref when cloning a single branch

packages/backend-common/src/scm/git.ts

@@ -86,13 +86,14 @@ export class Git {
     return git.commit({ fs, dir, message, author, committer });
   }
 
-  async clone({ url, dir }: { url: string; dir: string }): Promise<void> {
+  async clone({ url, dir, ref }: { url: string; dir: string; ref?: string }): Promise<void> {
     this.config.logger?.info(`Cloning repo {dir=${dir},url=${url}}`);
     return git.clone({
       fs,
       http,
       url,
       dir,
+      ref,
       singleBranch: true,
       depth: 1,
       onProgress: this.onProgressHandler(),

plugins/scaffolder-backend/src/scaffolder/stages/prepare/gitlab.ts

@@ -42,6 +42,7 @@ export class GitlabPreparer implements PreparerBase {
 
     const parsedGitLocation = parseGitUrl(location);
     const repositoryCheckoutUrl = parsedGitLocation.toString('https');
+    const ref = parsedGitLocation.toString('ref');
     const tempDir = await fs.promises.mkdtemp(
       path.join(workingDirectory, templateId),
     );
@@ -61,6 +62,7 @@ export class GitlabPreparer implements PreparerBase {
 
     await git.clone({
       url: repositoryCheckoutUrl,
+      ref: ref,
       dir: tempDir,
     });