TST: fix test_basic failure on Windows

[cgohlke]

Echo is a command in the Windows command interpreter

Fix one test failure of numpy-1.13.0rc1+mkl on Windows:

NumPy version 1.13.0rc1
NumPy relaxed strides checking option: True
NumPy is installed in X:\Python36\lib\site-packages\numpy
Python version 3.6.1 (v3.6.1:69c0db5, Mar 21 2017, 18:41:36) [MSC v.1900 64 bit (AMD64)]
nose version 1.3.7
<snip>
======================================================================
FAIL: test_basic (test_exec_command.TestExecCommand)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "X:\Python36\lib\site-packages\numpy\distutils\tests\test_exec_command.py", line 212, in test_basic
    self.check_nt(use_tee=0)
  File "X:\Python36\lib\site-packages\numpy\distutils\tests\test_exec_command.py", line 103, in check_nt
    self.assertEqual(s, 0)
AssertionError: 127 != 0

----------------------------------------------------------------------
Ran 6191 tests in 25.453s

FAILED (KNOWNFAIL=8, SKIP=11, failures=1) 

[charris]

@cgohlke Thanks @cgohlke . Could you forward port this so that it is against the master branch?

EDIT: nvm, already done.

[eric-wieser]

Why would appveyor not catch this?

[charris]

@eric-wieser I wondered that too. There is probably some difference in the test environment that matters.

[cgohlke]

The easiest explanation why this does not fail on AppVeyor would be that there is a echo.exe in the executable search path, e.g. as part of a git, mingw, or msys installation.

[charris]

@cgohlke Likely, it is running in a miniconda environment.

[cgohlke]

The AppVeyor Visual Studio build environments have git installed (https://www.appveyor.com/docs/build-environment/#pre-installed-software).