add missing decode in -w option of build_sphinx
add missing decode in -w option of build_sphinx

Cadair/astropy-helpers,bsipocz/astropy-helpers,astropy/astropy-helpers,embray/astropy_helpers,Cadair/astropy-helpers,embray/astropy_helpers,larrybradley/astropy-helpers,embray/astropy_helpers,dpshelio/astropy-helpers,larrybradley/astropy-helpers,embray/astropy_helpers,bsipocz/astropy-helpers,astropy/astropy-helpers,dpshelio/astropy-helpers,larrybradley/astropy-helpers,bsipocz/astropy-helpers