Fix submodules not synced for repeated repo

If I check out e.g. multiple branches of the same repo in one
manifest, only the submodules of one checkout are synced.

Fix this by adding the relative path  of the checkout as a key
to the mapping of derived projects, preventing overwrite.

The fix was originally proposed here:
https://issues.gerritcodereview.com/issues/40013218

Bug: 40013218
Change-Id: Ia86518ccf2c0af7bd7e4daf8d703a55b7e10ba52
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/581062
Reviewed-by: Mike Frysinger <vapier@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Josef Malmstrom <Josef.Malmstrom@arm.com>
Tested-by: Josef Malmstrom <Josef.Malmstrom@arm.com>

command.py

@@ -412,7 +412,8 @@ class Command:
             for project in all_projects_list:
                 if submodules_ok or project.sync_s:
                     derived_projects.update(
-                        (p.name, p) for p in project.GetDerivedSubprojects()
+                        (p.RelPath(local=False), p)
+                        for p in project.GetDerivedSubprojects()
                     )
             all_projects_list.extend(derived_projects.values())
             for project in all_projects_list:

tests/test_command.py

@@ -0,0 +1,88 @@
+# Copyright (C) 2026 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Unittests for the command.py module."""
+
+from command import Command
+
+
+class FakeProject:
+    """Minimal project double for Command.GetProjects tests."""
+
+    def __init__(
+        self,
+        name,
+        relpath,
+        *,
+        gitdir=None,
+        derived_subprojects=None,
+        sync_s=False,
+    ):
+        self.name = name
+        self.relpath = relpath
+        self.gitdir = gitdir or f"/git/{relpath}"
+        self.sync_s = sync_s
+        self.Exists = True
+        self._derived_subprojects = derived_subprojects or []
+
+    def GetDerivedSubprojects(self):
+        return list(self._derived_subprojects)
+
+    def MatchesGroups(self, _groups):
+        return True
+
+    def RelPath(self, local=True):
+        return self.relpath
+
+
+class FakeManifest:
+    """Minimal manifest double for Command.GetProjects tests."""
+
+    def __init__(self, projects):
+        self.projects = projects
+
+    def GetManifestGroupsStr(self):
+        return "default"
+
+
+def test_get_projects_keeps_derived_subprojects_for_repeated_repo():
+    """Derived subprojects are keyed by checkout path, not repo identity."""
+    submodule_a = FakeProject(
+        "submodule",
+        "src/one/submodule",
+        gitdir="/shared/modules/submodule.git",
+    )
+    submodule_b = FakeProject(
+        "submodule",
+        "src/two/submodule",
+        gitdir="/shared/modules/submodule.git",
+    )
+    project_a = FakeProject(
+        "project",
+        "src/one",
+        derived_subprojects=[submodule_a],
+        sync_s=True,
+    )
+    project_b = FakeProject(
+        "project",
+        "src/two",
+        derived_subprojects=[submodule_b],
+        sync_s=True,
+    )
+    manifest = FakeManifest([project_a, project_b])
+    cmd = Command(manifest=manifest)
+
+    projects = cmd.GetProjects([])
+
+    assert set(projects) == {project_a, project_b, submodule_a, submodule_b}