Running
```
from pathlib import Path
import numpy as np
np.arange(300000) / Path("foo")
```
raises
```
TypeError: argument should be a path or str object, not <class 'int'>

During handling of the above exception, another exception occurred:

SystemError: <built-in method __new__ of type object at 0x7fb4df227fc0> returned a result with an error set

<elided: many repeats of the same>

During handling of the above exception, another exception occurred:

SystemError: <built-in method __new__ of type object at 0x7fb4df227fc0> returned a result with an error set

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/tmp/foo.py", line 3, in <module>
    np.arange(300000) / Path("foo")
  File "/usr/lib/python3.5/pathlib.py", line 879, in __rtruediv__
    return self._from_parts([key] + self._parts)
  File "/usr/lib/python3.5/pathlib.py", line 637, in _from_parts
    self = object.__new__(cls)
SystemError: <built-in method __new__ of type object at 0x7fb4df227fc0> returned a result with an error set
```
Note that this does NOT appear for small arrays; I haven't determined the threshold.
Crossposted as https://github.com/numpy/numpy/issues/7360.