pycompat: allow pycompat.sysbytes() even if input already is bytes pycompat.sysstr() on py3 accepts an input that's already str (i.e. unicode). This patch makes it so pycompat.sysbytes() on py3 accepts an input that's already bytes. Allowing that makes it possible to do pycompat.sysbytes(fp.name) where fp.name is either bytes or unicode, as we'll get when fp can come from either open() or resources.open_binary(). Differential Revision: https://phab.mercurial-scm.org/D7621