pyYaml install fails on Windows 10

Issue #342 on hold
enok123
created an issue

My tox.ini file looks like this on windows

[tox]
envlist = cpy27,dpy27
skip_missing_interpreters = True

[testenv]

basepython =
    cpy27: C:\Python27\python.exe
    dpy27: D:\Python27\python.exe

deps =
    pytest  

commands = py.test tests

But when I do "tox" from command prompt, I'm seeing this error. Why is this? I don't see any error, if I run python setup.py install on command line

Installing collected packages: coverage, pytest-cov, requests, psutil, pytz, enum, argh, pathtools, PyYAML, watchdog, monit
  Running setup.py install for PyYAML: started
    Running setup.py install for PyYAML: finished with status 'error'
    Complete output from command d:\repos\wevedata\datapipeline\monit\.tox\dpy27\scripts\python.exe -u -c "import setuptools, tokenize;__file__='c:\\users\\vikone\\appdata\\local\\temp\\pip-build-bbx8kz\\PyYAML\\setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record c:\users\vikone\appdata\local\temp\pip-zyvbbh-record\install-record.txt --single-version-externally-managed --compile --install-headers d:\repos\wevedata\datapipeline\monit\.tox\dpy27\include\site\python2.7\PyYAML:
    running install
    running build
    running build_py
    creating build
    creating build\lib.win-amd64-2.7
    creating build\lib.win-amd64-2.7\yaml
    copying lib\yaml\composer.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\constructor.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\cyaml.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\dumper.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\emitter.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\error.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\events.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\loader.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\nodes.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\parser.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\reader.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\representer.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\resolver.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\scanner.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\serializer.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\tokens.py -> build\lib.win-amd64-2.7\yaml
    copying lib\yaml\__init__.py -> build\lib.win-amd64-2.7\yaml
    running build_ext
    creating build\temp.win-amd64-2.7
    creating build\temp.win-amd64-2.7\Release
    checking if libyaml is compilable
    error: [Error 2] The system cannot find the file specified