gyb: force I/O in UTF-8
gyb: force I/O in UTF-8

We would rely on the system encoding, which if unspecified would fall
back to `C` treating the encoding as ASCII.  This fails with unicode
data in Python3.  Thanks to @tbkka for the brilliant idea of forcing the
encoding when reading the file.  This improves the test pass rate on
Linux with Python 3.

glessard/swift,CodaFi/swift,gregomni/swift,tkremenek/swift,tkremenek/swift,apple/swift,nathawes/swift,benlangmuir/swift,xwu/swift,allevato/swift,glessard/swift,CodaFi/swift,rudkx/swift,atrick/swift,xwu/swift,gregomni/swift,ahoppen/swift,jmgc/swift,JGiola/swift,hooman/swift,jmgc/swift,rudkx/swift,benlangmuir/swift,rudkx/swift,parkera/swift,airspeedswift/swift,xwu/swift,JGiola/swift,jckarter/swift,hooman/swift,jmgc/swift,atrick/swift,allevato/swift,airspeedswift/swift,benlangmuir/swift,nathawes/swift,roambotics/swift,CodaFi/swift,JGiola/swift,benlangmuir/swift,jckarter/swift,allevato/swift,jmgc/swift,parkera/swift,parkera/swift,jckarter/swift,hooman/swift,apple/swift,CodaFi/swift,roambotics/swift,CodaFi/swift,glessard/swift,tkremenek/swift,ahoppen/swift,nathawes/swift,tkremenek/swift,ahoppen/swift,gregomni/swift,rudkx/swift,jmgc/swift,ahoppen/swift,ahoppen/swift,benlangmuir/swift,jckarter/swift,airspeedswift/swift,CodaFi/swift,allevato/swift,hooman/swift,apple/swift,airspeedswift/swift,jckarter/swift,benlangmuir/swift,tkremenek/swift,tkremenek/swift,jmgc/swift,atrick/swift,rudkx/swift,roambotics/swift,gregomni/swift,nathawes/swift,roambotics/swift,jmgc/swift,airspeedswift/swift,JGiola/swift,rudkx/swift,parkera/swift,hooman/swift,parkera/swift,nathawes/swift,xwu/swift,hooman/swift,parkera/swift,atrick/swift,hooman/swift,xwu/swift,gregomni/swift,gregomni/swift,glessard/swift,roambotics/swift,jckarter/swift,jckarter/swift,nathawes/swift,atrick/swift,apple/swift,allevato/swift,atrick/swift,allevato/swift,nathawes/swift,roambotics/swift,allevato/swift,parkera/swift,tkremenek/swift,apple/swift,JGiola/swift,xwu/swift,glessard/swift,airspeedswift/swift,apple/swift,parkera/swift,ahoppen/swift,xwu/swift,CodaFi/swift,airspeedswift/swift,glessard/swift,JGiola/swift