Starting from https://build.chromium.org/p/chromium.gpu.fyi/builders/GPU%20Win%20Clang%20Builder%20%28dbg%29/builds/4836 the install_static_unittests_run rule fails with 

E:\b\depot_tools\python276_bin\python.exe gyp-win-tool action-wrapper environment.x86 install_static_unittests_run_target_isolate_505e5a847558b720a0ef83d1cbafd202.8c6a326aa7c39f12a19f31e474b8425f.rsp ..\..\chrome
Traceback (most recent call last):

  File "../tools/isolate_driver.py", line 313, in <module>

    sys.exit(main())

  File "../tools/isolate_driver.py", line 297, in main

    create_wrapper(args, isolate, isolated)

  File "../tools/isolate_driver.py", line 212, in create_wrapper

    assert os.path.basename(isolate) == isolate, isolate

AssertionError: install_static\install_static_unittests.isolate

ananta@, it seems very related to your changes in https://codereview.chromium.org/2017853002, can you take a look?