issue when running python -m spectral.tests.run`

[YannChemin]

`------------------------------------------------------------------------
Running SpyFile read tests on BSQ complex128 little-endian file without memmap...

Testing getitem_i_j......................................... OK
Testing getitem_i_j_k....................................... OK
Testing getitem_i_j_kslice.................................. OK
Testing getitem_islice_jslice............................... OK
Testing load................................................ OK
Testing read_band........................................... OK
Testing read_bands.......................................... OK
Testing read_bands_duplicates............................... OK
Testing read_bands_nonascending............................. OK
Testing read_datum.......................................... OK
Testing read_pixel.......................................... OK
Testing read_subimage....................................... OK
Testing read_subregion...................................... OK
Traceback (most recent call last):
File "", line 198, in _run_module_as_main
File "", line 88, in _run_code
File "/home/yann/dev/spectral/spectral/tests/run.py", line 43, in
test.run()
File "/home/yann/dev/spectral/spectral/tests/spyfile.py", line 342, in run
tests = create_complex_test_files(dtypes)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/yann/dev/spectral/spectral/tests/spyfile.py", line 314, in create_complex_test_files
spy.envi.save_image(fname, X)
File "/home/yann/dev/spectral/spectral/io/envi.py", line 455, in save_image
_write_image(hdr_file, data, metadata, **kwargs)
File "/home/yann/dev/spectral/spectral/io/envi.py", line 678, in _write_image
(hdr_file, img_file) = check_new_filename(hdr_file, img_ext, force)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/yann/dev/spectral/spectral/io/envi.py", line 375, in check_new_filename
raise EnviException('Header file %s already exists. Use force '
spectral.io.envi.EnviException: Header file /home/yann/dev/spectral/spectral_test_files/test_complex64.hdr already exists. Use force keyword to force overwrite.
`