Setting numba threading layer triggers other numba bug

[ivirshup]

Setting the default threading layer here:

umap/umap/__init__.py

Lines 3 to 6 in c61cdfe

	# Workaround: https://github.com/numba/numba/issues/3341
	import numba
	numba.config.THREADING_LAYER = "workqueue"

Causes the workaround of installing tbb for this (numba/numba#4484) numba parallelism bug not to work.

It's a little unclear to me if the original issue is resolved. If so, could these lines just get removed?

[sleighsoft]

Good catch! That is something that should be removed from 0.4-dev once tbb is the standard.

[sleighsoft]

Will be resolved in 0.4