handle unrelated history promotion fallback

src/apps/apps.service.ts

@@ -645,8 +645,22 @@ export class AppsService {
       const normalized = message.toLowerCase();
       return normalized.includes('refusing to merge unrelated histories') || normalized.includes('not possible to fast-forward');
     };
+    const gitUserName = this.configService.get<string>(
+      'GIT_USER_NAME',
+      'Autonomy Studio Bot',
+    );
+    const gitUserEmail = this.configService.get<string>(
+      'GIT_USER_EMAIL',
+      'studio-ci@autonomystudio.local',
+    );
     const workRoot = path.join(os.tmpdir(), 'studio-admin-release-promotions');
     await fs.mkdir(workRoot, { recursive: true });
+    const mergeOptions = [
+      '-c',
+      `user.name=${gitUserName}`,
+      '-c',
+      `user.email=${gitUserEmail}`,
+    ];
 
     for (const [repository, commitSha] of byRepository) {
       const workDir = path.join(workRoot, `${sanitizeImageName(repository)}-${Date.now()}`);
@@ -669,6 +683,17 @@ export class AppsService {
           targetBranch,
         ], { cwd: workDir }).catch(() => undefined);
 
+        await execFileAsync(gitBin, [
+          'config',
+          'user.name',
+          gitUserName,
+        ], { cwd: workDir });
+        await execFileAsync(gitBin, [
+          'config',
+          'user.email',
+          gitUserEmail,
+        ], { cwd: workDir });
+
         const targetExists = await gitRefExists(workDir, `refs/remotes/origin/${targetBranch}`, gitBin);
         if (targetExists) {
           await execFileAsync(gitBin, [
@@ -679,6 +704,7 @@ export class AppsService {
           ], { cwd: workDir });
           try {
             await execFileAsync(gitBin, [
+              ...mergeOptions,
               'merge',
               '--ff-only',
               commitSha,
@@ -689,6 +715,7 @@ export class AppsService {
               throw error;
             }
             await execFileAsync(gitBin, [
+              ...mergeOptions,
               'merge',
               '--allow-unrelated-histories',
               '--no-ff',