Use a different (better?) approach to map host users to container users.
diff --git a/buildkite/bazelci.py b/buildkite/bazelci.py
index ca50ca4..71caf1b 100755
--- a/buildkite/bazelci.py
+++ b/buildkite/bazelci.py
@@ -1566,10 +1566,12 @@
                 "network": "host",
                 "privileged": True,
                 "propagate-environment": True,
+                "propagate-uid-gid": True,
                 "volumes": [
+                    "/etc/group:/etc/group:ro",
+                    "/etc/passwd:/etc/passwd:ro",
                     "/opt:/opt:ro",
-                    "/var/lib/bazel-cache:/home/bazel/.cache/bazel/_bazel_bazel/cache",
-                    "/var/lib/bazel-root-cache:/root/.cache/bazel/_bazel_root/cache",
+                    "/var/lib/buildkite-agent:/var/lib/buildkite-agent",
                     "/var/lib/gitmirrors:/var/lib/gitmirrors:ro",
                     "/var/run/docker.sock:/var/run/docker.sock",
                 ],