TST: Simplify assert_warns in test_io.py
TST: Simplify assert_warns in test_io.py

seberg/numpy,seberg/numpy,anntzer/numpy,simongibbons/numpy,madphysicist/numpy,jakirkham/numpy,simongibbons/numpy,anntzer/numpy,madphysicist/numpy,mhvk/numpy,charris/numpy,grlee77/numpy,pbrod/numpy,charris/numpy,madphysicist/numpy,grlee77/numpy,mhvk/numpy,mattip/numpy,numpy/numpy,endolith/numpy,simongibbons/numpy,pbrod/numpy,pbrod/numpy,mattip/numpy,rgommers/numpy,mhvk/numpy,jakirkham/numpy,anntzer/numpy,pdebuyl/numpy,mattip/numpy,simongibbons/numpy,pbrod/numpy,grlee77/numpy,anntzer/numpy,seberg/numpy,abalkin/numpy,numpy/numpy,seberg/numpy,jakirkham/numpy,mattip/numpy,jakirkham/numpy,mhvk/numpy,pdebuyl/numpy,grlee77/numpy,charris/numpy,endolith/numpy,rgommers/numpy,pdebuyl/numpy,charris/numpy,abalkin/numpy,madphysicist/numpy,simongibbons/numpy,grlee77/numpy,abalkin/numpy,rgommers/numpy,numpy/numpy,madphysicist/numpy,mhvk/numpy,endolith/numpy,pbrod/numpy,pdebuyl/numpy,jakirkham/numpy,numpy/numpy,rgommers/numpy,endolith/numpy