[yt-dev] Issue #1059: Enzo nuclei density does not precisely equal sum of species densities in python 3 (yt_analysis/yt)

[Nathan Goldbaum]

New issue 1059: Enzo nuclei density does not precisely equal sum of species densities in python 3
https://bitbucket.org/yt_analysis/yt/issues/1059/enzo-nuclei-density-does-not-precisely

Nathan Goldbaum:

John ZuHone offers this repro script that illustrates the issue:


```
#!python

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from __future__ import print_function
import yt
from yt.testing import assert_array_equal
import numpy as np
from IPython import embed

ecp = "enzo_cosmology_plus/DD0046/DD0046"
ds = yt.load(ecp)
dd = ds.all_data()
a = dd["He_nuclei_density"]
b = dd["He_number_density"] + dd["He_p1_number_density"] + dd["He_p2_number_density"]

err = np.abs(a-b)/a
print(np.max(err))
assert_array_equal(a,b)
```

This is currently causing one of the Enzo answer tests to fail on python3.