Convert using utf-8 instead of ascii in safe_str()
Convert using utf-8 instead of ascii in safe_str()

This way we don't lose information and the returned string is
ascii-compatible anyway

nicoddemus/pytest,RonnyPfannschmidt/pytest,MichaelAquilina/pytest,hackebrot/pytest,tareqalayan/pytest,pytest-dev/pytest,skylarjhdownes/pytest,The-Compiler/pytest,alfredodeza/pytest,tomviner/pytest,jaraco/pytest,flub/pytest,tgoodlet/pytest,nicoddemus/pytest,rmfitzpatrick/pytest,Akasurde/pytest,The-Compiler/pytest,txomon/pytest,markshao/pytest,davidszotten/pytest,tomviner/pytest,ddboline/pytest,pfctdayelise/pytest