The test test_Sentinel2_image_processor fails inconsistantly

[andrewphilipsmith]

(Note: This issue was initially opened here urbangrammarai#20)

How to reproduce

Run this test in isolation twice:

$ pytest pyveg/tests/test_processor_modules.py::test_Sentinel2_image_processor

Expect behaviour

The test should give the same result on every run (assuming no other changes)

Actual behaviour

The test gives different results on subsequent runs - passing on one occasion and failing the other.
This behaviour is more inconsistent when run as part of the entire test suite.

Notes

My initial impression is that this is due to the test failing to remove any temporary output files, which then interfere with (a) other tests and (b) future runs on this test.