The current test output from master win32 phobos (https://auto-tester.puremagic.com/test_data.ghtml?projectid=1&runid=66825&logid=6).

    ../dmd/src/dmd -O -w -L/co -unittest unittest.d unittest1.obj unittest2.obj unittest2a.obj  unittest3.obj unittest3a.obj unittest3b.obj unittest4.obj  unittest5.obj unittest6.obj unittest7.obj unittest8.obj  etc\c\zlib\zlib.lib ..\druntime\lib\druntime.lib

    unittest
    The system cannot find the path specified.
    args.length = 1
    args[0] = 'unittest.exe'
    Success!

Sometimes this also fails with:

    unittest
    Error: 'unittest' not found

Can someone please look into this?
Seems like the link step silently fails, so this might be an issue on the auto-tester.