fix tests/test_linear_solvers.py for no umfpack
fix tests/test_linear_solvers.py for no umfpack

vlukes/sfepy,rc/sfepy,rc/sfepy,BubuLK/sfepy,sfepy/sfepy,sfepy/sfepy,sfepy/sfepy,BubuLK/sfepy,vlukes/sfepy,BubuLK/sfepy,vlukes/sfepy,rc/sfepy