sh_spec.py should only output utf-8 as well.

This fixes a crash that only happened when running 'test/spec.sh all',
not test/spec.sh var-op-other.  I think the encoding that Python uses
deepends on the terminal that stdout is connected to?

test/sh_spec.py

@@ -770,10 +770,12 @@ def _WriteRaw(s):
        # We output utf-8-encoded HTML.  If we get invalid utf-8 as stdout
        # (which is very possible), then show the ASCII repr().
        try:
          s2 = s.decode('utf-8')
          s.decode('utf-8')
        except UnicodeDecodeError:
          s2 = repr(s)  # ASCII representation
        self.f.write(cgi.escape(s2))
          valid_utf8 = repr(s)  # ASCII representation
        else:
          valid_utf8 = s
        self.f.write(cgi.escape(valid_utf8))
        self.f.write('</pre>')

      self.f.write('<i>stdout:</i> <br/>\n')