Get next char from raw queue.

        Raise EOFError when connection is closed.

def rawq_getchar(self):
        """Get next char from raw queue.

        Raise EOFError when connection is closed.
        """
        if not self.rawq:
            yield from self.fill_rawq()
            if self.eof:
                raise EOFError
        c = self.rawq[self.irawq:self.irawq + 1]
        self.irawq = self.irawq + 1
        if self.irawq >= len(self.rawq):
            self.rawq = b''
            self.irawq = 0
        return c