diff --git a/tools/batch-rebase/src/batch_rebase/main.py b/tools/batch-rebase/src/batch_rebase/main.py
index 51e08d0437ef114216ae32d172d96b880ad2e9da..3eaa6c007613f6e2e4e11955f1e3545fe8c7a721 100755
--- a/tools/batch-rebase/src/batch_rebase/main.py
+++ b/tools/batch-rebase/src/batch_rebase/main.py
@@ -41,6 +41,10 @@ def info(msg):
 def warn(msg):
     logging.warning(msg)
 
+def error(msg):
+    logging.error(msg)
+
+
 def get_nested_key(conf, key):
     for k in key:
         conf = conf[k]
@@ -225,7 +229,10 @@ def do_create(conf_folder, repo, temp_repo, new_branch, conf, persistent_tags, t
 
     # Create the new branch at the beginning of the cherry picking session
     base = conf['base']
-    git(['fetch', '--', base['remote'], base['ref']])
+    base_ref = base['ref']
+    remote = base['remote']
+    remote_base = remote_tracking(remote, base_ref)
+    git(['fetch', '--', remote, f'{base_ref}:{remote_base}'])
     git(['checkout', '-b', new_branch, 'FETCH_HEAD'])
 
     # Start cherry picking topics
@@ -273,6 +280,10 @@ def do_cherry_pick(repo, temp_repo, conf, persistent_tags, tags_suffix, branch,
     return (not has_conflict, 1 if has_conflict else 0)
 
 
+def remote_tracking(remote, tip):
+    return f'refs/remotes/{remote}/batch-rebase-tips/{tip}'
+
+
 def _do_cherry_pick(repo, conf, persistent_tags, tags_suffix):
     git = make_git_func(repo)
 
@@ -367,18 +378,20 @@ def _do_cherry_pick(repo, conf, persistent_tags, tags_suffix):
             nr_commits = topic.get('nr-commits')
 
             # Fetch the topic base and tip
-            git(['fetch', '--', remote, tip])
+            remote_tip = remote_tracking(remote, tip)
+            git(['fetch', '--', remote, f'{tip}:{remote_tip}'])
+            tip = remote_tip
 
             if base is not None:
-                git(['fetch', '--', remote, base])
+                remote_base = remote_tracking(remote, base)
+                git(['fetch', '--', remote, f'{base}:{remote_base}'])
+                base = remote_base
             elif nr_commits is not None:
                 base = f'{tip}~{nr_commits}'
             else:
                 raise ValueError(f'base or nr-commits need to be set on topic "{name}"')
 
-            range_base = f'refs/remotes/{remote}/{base}'
-            range_tip = f'refs/remotes/{remote}/{tip}'
-            range_ref = f'{range_base}..{range_tip}'
+            range_ref = f'{base}..{tip}'
             range_sha1s = list(reversed(git(['rev-list', range_ref], capture=True).splitlines()))
 
             nr_commits = len(range_sha1s)
diff --git a/tools/lisa-combine-gitlab-mr/src/lisa_combine_gitlab_mr/main.py b/tools/lisa-combine-gitlab-mr/src/lisa_combine_gitlab_mr/main.py
index 8ba752b7a2b768d8f29f9b2b9b40ddad974d2bc0..933ea6ffa5c10cf6395e93e1bed136dfa0227f04 100755
--- a/tools/lisa-combine-gitlab-mr/src/lisa_combine_gitlab_mr/main.py
+++ b/tools/lisa-combine-gitlab-mr/src/lisa_combine_gitlab_mr/main.py
@@ -47,24 +47,26 @@ def get_gitlab_mrs(api_url, project_id, api_token=None, state="opened", scope="a
         r.raise_for_status()
         return r
 
+    # Get the clone URL of the original repo
+    clone_url = call_gitlab_api(
+        f"projects/{project_id}"
+    ).json()['http_url_to_repo']
+
     def get_mr(mr):
-        # populate commits count - use another api
+        iid = mr['iid']
         mr_commit_response = call_gitlab_api(
-            f"projects/{project_id}/merge_requests/{mr['iid']}/commits"
+            f"projects/{project_id}/merge_requests/{iid}/commits"
         )
         mr_commit_response = mr_commit_response.json()
         assert isinstance(mr_commit_response, list)
         commits_count = len(mr_commit_response)
 
-        # mr could be from a fork - use another api
-        project_response = call_gitlab_api(
-            f"projects/{mr['source_project_id']}"
-        )
-        clone_url = project_response.json()['http_url_to_repo']
-
         return dict(
             sha=mr['sha'],
-            source_branch=mr['source_branch'],
+            # We use the magic branch associated with the merge-request instead
+            # of the "real" source branch and its associated repo, as the
+            # latter could be a private fork we don't have direct access to.
+            source_branch=f'refs/merge-requests/{iid}/head',
             commits_count=commits_count,
             clone_url=clone_url,
         )