Bazel CI flaky error __main__.BazelExternalRepositoryTest testNewHttpTarArchiveWithSymlinks

CI: https://buildkite.com/organizations/bazel/analytics/suites/bazel-bazel/tests/018a9945-300c-7030-a16b-dff6d58298a8?branch=master

BAZELCI_TASK=rbe_ubuntu2004
TEST_TARGET=//src/test/py/bazel:bazel_external_repository_test
TEST_NAME=testNewHttpTarArchiveWithSymlinks

bazel test //src/test/py/bazel:bazel_external_repository_test --test_filter=testNewHttpTarArchiveWithSymlinks

Logs:
```
Traceback (most recent call last):
File "/b/f/w/bazel-out/k8-fastbuild/bin/src/test/py/bazel/bazel_external_repository_test.runfiles/_main/src/test/py/bazel/bazel_external_repository_test.py", line 162, in testNewHttpTarArchiveWithSymlinks
self.RunBazel([
File "/b/f/w/bazel-out/k8-fastbuild/bin/src/test/py/bazel/bazel_external_repository_test.runfiles/_main/src/test/py/bazel/test_base.py", line 424, in RunBazel
return self.RunProgram(
File "/b/f/w/bazel-out/k8-fastbuild/bin/src/test/py/bazel/bazel_external_repository_test.runfiles/_main/src/test/py/bazel/test_base.py", line 580, in RunProgram
self.AssertExitCode(exit_code, 0, stderr_lines, stdout_lines)
File "/b/f/w/bazel-out/k8-fastbuild/bin/src/test/py/bazel/bazel_external_repository_test.runfiles/_main/src/test/py/bazel/test_base.py", line 191, in AssertExitCode
self._AssertExitCodeIs(actual_exit_code, lambda x: x == expected_exit_code,
File "/b/f/w/bazel-out/k8-fastbuild/bin/src/test/py/bazel/bazel_external_repository_test.runfiles/_main/src/test/py/bazel/test_base.py", line 176, in _AssertExitCodeIs
self.fail('\n'.join([
AssertionError: Bazel exited with 48 (expected 0), stderr:

```

CC Greenteam @meteorcloudy

Start with src/test/py/bazel/bazel_external_repository_test.py, focusing on testNewHttpTarArchiveWithSymlinks, and run the provided filtered test command in the rbe_ubuntu2004 configuration. Review the linked CI logs and the exit-code handling in src/test/py/bazel/test_base.py. Done means the test no longer flakes and passes reliably in that CI task.

Written by the indexing model from the issue text.