[yt-dev] Issue #1254: Windows test failure: alt_ray_tracers (yt_analysis/yt)

[Nathan Goldbaum]

New issue 1254: Windows test failure: alt_ray_tracers
https://bitbucket.org/yt_analysis/yt/issues/1254/windows-test-failure-alt_ray_tracers

Nathan Goldbaum:

Currently this is causing our python2.7 appveyor builds to fail:

```
Traceback (most recent call last):
  File "C:\Miniconda-x64\envs\test\lib\site-packages\nose\loader.py", line 251, in generate
    for test in g():
  File "c:\projects\yt\yt\utilities\lib\tests\test_alt_ray_tracers.py", line 65, in test_cylindrical_ray_trace
    t, s, rztheta, inds = cylindrical_ray_trace(p1, p2, left_grid, right_grid)
  File "yt\utilities\lib\alt_ray_tracers.pyx", line 203, in yt.utilities.lib.alt_ray_tracers.cylindrical_ray_trace (yt/utilities/lib/alt_ray_tracers.c:6000)
    tsect, tinds = np.unique(tsect[tmask], return_index=True)
ValueError: Item size of buffer (1 byte) does not match size of 'int64_t' (8 bytes)
```

https://ci.appveyor.com/project/Xarthisius/yt/build/1.0.194/job/p8fgpx0vhx7q5098