diff --git a/contrib/automation/hgautomation/linux.py b/contrib/automation/hgautomation/linux.py
--- a/contrib/automation/hgautomation/linux.py
+++ b/contrib/automation/hgautomation/linux.py
@@ -489,7 +489,11 @@ def synchronize_hg(source_path: pathlib.
             'ssh://%s//hgwork/src' % public_ip,
         ]
 
-        subprocess.run(args, cwd=str(source_path), env=env, check=True)
+        res = subprocess.run(args, cwd=str(source_path), env=env)
+
+        # Allow 1 (no-op) to not trigger error.
+        if res.returncode not in (0, 1):
+            res.check_returncode()
 
         # TODO support synchronizing dirty working directory.
 
diff --git a/contrib/automation/hgautomation/windows.py b/contrib/automation/hgautomation/windows.py
--- a/contrib/automation/hgautomation/windows.py
+++ b/contrib/automation/hgautomation/windows.py
@@ -180,7 +180,11 @@ def synchronize_hg(hg_repo: pathlib.Path
             'ssh://%s/c:/hgdev/src' % public_ip,
         ]
 
-        subprocess.run(args, cwd=str(hg_repo), env=env, check=True)
+        res = subprocess.run(args, cwd=str(hg_repo), env=env)
+
+        # Allow 1 (no-op) to not trigger error.
+        if res.returncode not in (0, 1):
+            res.check_returncode()
 
         run_powershell(winrm_client,
                        HG_UPDATE_CLEAN.format(revision=full_revision))