Fix EFS clone HEAD pointing to wrong branch after fetch+reset

services/git/git_clone_to_efs.py

@@ -4,6 +4,7 @@
 from services.git.resolve_git_locks import resolve_git_locks
 from utils.command.run_subprocess_async import run_subprocess_async
 from utils.error.handle_exceptions import handle_exceptions
+from utils.files.read_local_file import read_local_file
 from utils.logging.logging_config import logger
 
 # clone_tasks example:
@@ -55,15 +56,21 @@ async def git_clone_to_efs(efs_dir: str, clone_url: str, branch: str):
             ["git", "fetch", "--depth", "1", "origin", branch], efs_dir
         )
         if returncode == 0:
-            fetch_head = os.path.join(efs_git_dir, "FETCH_HEAD")
-            if os.path.exists(fetch_head):
-                with open(fetch_head, encoding="utf-8") as f:
-                    logger.info("FETCH_HEAD: %s", f.read().strip())
+            fetch_head_content = read_local_file("FETCH_HEAD", efs_git_dir)
+            if fetch_head_content:
+                logger.info("FETCH_HEAD: %s", fetch_head_content.strip())
             else:
                 logger.warning("FETCH_HEAD missing despite fetch success")
             await run_subprocess_async(
                 ["git", "reset", "--hard", "FETCH_HEAD"], efs_dir
             )
+            # Switch HEAD to the correct branch if it changed (e.g. master → release/20260408)
+            head_content = read_local_file("HEAD", efs_git_dir)
+            current_ref = head_content.strip() if head_content else ""
+            if current_ref != f"ref: refs/heads/{branch}":
+                await run_subprocess_async(
+                    ["git", "checkout", "-B", branch, "FETCH_HEAD"], efs_dir
+                )
         return efs_dir
 
     # Always use init + fetch + checkout instead of clone

services/git/test_git_clone_to_efs.py

@@ -1,6 +1,6 @@
 # pylint: disable=unused-argument
 # pyright: reportUnusedVariable=false
-from unittest.mock import patch, AsyncMock
+from unittest.mock import AsyncMock, patch
 
 import pytest
 
@@ -136,11 +136,19 @@ async def test_git_clone_updates_origin_url_before_fetch(mock_os_makedirs):
             mock_run.return_value = (0, "")
 
             fresh_url = "https://x-access-token:fresh_token@github.com/owner/repo.git"
-            with patch("builtins.open", create=True):
+            # FETCH_HEAD exists, HEAD already on main → checkout -B skipped
+            with patch(
+                "services.git.git_clone_to_efs.read_local_file",
+                side_effect=lambda f, _d: (
+                    "abc123\tbranch 'main'"
+                    if f == "FETCH_HEAD"
+                    else "ref: refs/heads/main"
+                ),
+            ):
                 result = await git_clone_to_efs("/mnt/efs/repo", fresh_url, "main")
 
             assert result == "/mnt/efs/repo"
-            # safe.directory + get-url + set-url + fetch + reset
+            # safe.directory + get-url + set-url + fetch + reset (no checkout -B, branch unchanged)
             assert mock_run.call_count == 5
             calls = [call[0][0] for call in mock_run.call_args_list]
             assert calls[0] == [
@@ -157,6 +165,45 @@ async def test_git_clone_updates_origin_url_before_fetch(mock_os_makedirs):
             assert calls[4] == ["git", "reset", "--hard", "FETCH_HEAD"]
 
 
+@pytest.mark.asyncio
+async def test_git_clone_switches_branch_when_target_changes(mock_os_makedirs):
+    """When target branch changed (e.g. master → release/20260408), checkout -B updates HEAD."""
+    with patch("services.git.git_clone_to_efs.os.path.exists") as mock_exists:
+        mock_exists.return_value = True
+
+        with patch(
+            "services.git.git_clone_to_efs.run_subprocess_async", new_callable=AsyncMock
+        ) as mock_run:
+            mock_run.return_value = (0, "")
+
+            clone_url = "https://github.com/owner/repo.git"
+            # HEAD on master, but fetching release/20260408 → checkout -B runs
+            with patch(
+                "services.git.git_clone_to_efs.read_local_file",
+                side_effect=lambda f, _d: (
+                    "abc123\tbranch 'release/20260408'"
+                    if f == "FETCH_HEAD"
+                    else "ref: refs/heads/master"
+                ),
+            ):
+                result = await git_clone_to_efs(
+                    "/mnt/efs/repo", clone_url, "release/20260408"
+                )
+
+            assert result == "/mnt/efs/repo"
+            # safe.directory + get-url + set-url + fetch + reset + checkout -B
+            assert mock_run.call_count == 6
+            calls = [call[0][0] for call in mock_run.call_args_list]
+            assert calls[4] == ["git", "reset", "--hard", "FETCH_HEAD"]
+            assert calls[5] == [
+                "git",
+                "checkout",
+                "-B",
+                "release/20260408",
+                "FETCH_HEAD",
+            ]
+
+
 @pytest.mark.asyncio
 async def test_git_clone_adds_origin_when_missing(mock_os_makedirs):
     """When .git exists but origin remote is missing, add origin instead of set-url."""
@@ -176,21 +223,21 @@ async def test_git_clone_adds_origin_when_missing(mock_os_makedirs):
             ]
 
             clone_url = "https://github.com/owner/repo.git"
-            with patch("builtins.open", create=True):
+            # HEAD already on main → checkout -B skipped
+            with patch(
+                "services.git.git_clone_to_efs.read_local_file",
+                side_effect=lambda f, _d: (
+                    "abc123\tbranch 'main'"
+                    if f == "FETCH_HEAD"
+                    else "ref: refs/heads/main"
+                ),
+            ):
                 result = await git_clone_to_efs("/mnt/efs/repo", clone_url, "main")
 
             assert result == "/mnt/efs/repo"
-            # safe.directory + get-url + add + fetch + reset
+            # safe.directory + get-url + add + fetch + reset (no checkout -B, branch unchanged)
             assert mock_run.call_count == 5
             calls = [call[0][0] for call in mock_run.call_args_list]
-            assert calls[0] == [
-                "git",
-                "config",
-                "--global",
-                "--add",
-                "safe.directory",
-                "/mnt/efs/repo",
-            ]
             assert calls[1] == ["git", "remote", "get-url", "origin"]
             assert calls[2] == ["git", "remote", "add", "origin", clone_url]
             assert calls[3] == ["git", "fetch", "--depth", "1", "origin", "main"]