getExtensionStubParserDirectory() currently resolves the test stub-parser directory from std::filesystem::current_path(). This is correct only while the server retains the test runner’s working directory.

When a test server is started with --fork, MongoDB’s daemonization path explicitly changes the process working directory to / before the daemon continues initialization. The test-only lookup can therefore resolve to /src/mongo/db/extension/test_examples instead of the server’s startup directory, causing aggregation_stage_fallback_parsers.json to be missed and preventing the expected fallback stub parsers from being registered.

Change the test-mode path resolution to use the startup cwd captured in serverGlobalParams.cwd as the base directory.

Note, this is not a bug in production, since production code paths resolve stub parsers from extensionsConfigPath.