make tests less verbose.
code simplification.
don't override another variable with the same name.
Don't schedule shapefeature replacement that are equivalent.
Add comment.
remove var not used.
rename var to don't override another var of the same name.
Make Join and GpuJoin raise error in make_node instead of run time.

At least, it was an error in Join at run time.
Allow numpy.asarray(cuda_ndarray, dtype=...)
pep8
remove unused import.
Update test that now the error is raised earlier.
Fix segfault introduced in this PR.
Fix potential crash.
Merge pull request #1524 from nouiz/fix_cycle

Fix cycle