tests/test-xdg.t

dispatch: convert exception payload to bytes more carefully

We were previously depending on str() doing something reasonable here,
and we can't depend on the objects in question supporting __bytes__,
so we work around the lack of direct bytes formatting.

#if no-windows no-osx

  $ mkdir -p xdgconf/hg
  $ echo '[ui]' > xdgconf/hg/hgrc
  $ echo 'username = foobar' >> xdgconf/hg/hgrc
  $ XDG_CONFIG_HOME="`pwd`/xdgconf" ; export XDG_CONFIG_HOME
  $ unset HGRCPATH
  $ hg config ui.username 2>/dev/null
  foobar

#endif