imported changes to umfpack.py from the removed module in scipy (which contained some improvements that were made to it while it was in scipy). original contributors of these changes are listed here: https://github.com/scipy/scipy/commits/master/scipy/sparse/linalg/dsolve/umfpack/umfpack.py
Merge pull request #1 from jrjohansson/master

imported changes to umfpack.py from the removed module in scipy