py3: create built in exceptions with str type messages in win32.py I hit an IOError in unlink() in test-pathconflicts-basic.t, that then crashed as it was handled: File "mercurial\dispatch.py", line 359, in _runcatch return _callcatch(ui, _runcatchfunc) File "mercurial\dispatch.py", line 367, in _callcatch return scmutil.callcatch(ui, func) File "mercurial\scmutil.py", line 252, in callcatch ui.error(_("abort: %s\n") % encoding.strtolocal(inst.strerror)) File "mercurial\encoding.py", line 205, in unitolocal return tolocal(u.encode('utf-8')) AttributeError: 'bytes' object has no attribute 'encode'