Wait for and read data being streamed from the daemon.

def read(self):
        "Wait for and read data being streamed from the daemon."
        if self.verbose > 1:
            sys.stderr.write("poll: reading from daemon...\n")
        eol = self.linebuffer.find('\n')
        if eol == -1:
            frag = self.sock.recv(4096)
            self.linebuffer += frag
            if self.verbose > 1:
                sys.stderr.write("poll: read complete.\n")
            if not self.linebuffer:
                if self.verbose > 1:
                    sys.stderr.write("poll: returning -1.\n")
                # Read failed
                return -1
            eol = self.linebuffer.find('\n')
            if eol == -1:
                if self.verbose > 1:
                    sys.stderr.write("poll: returning 0.\n")
                # Read succeeded, but only got a fragment
                return 0
        else:
            if self.verbose > 1:
                sys.stderr.write("poll: fetching from buffer.\n")

        # We got a line
        eol += 1
        self.response = self.linebuffer[:eol]
        self.linebuffer = self.linebuffer[eol:]

        # Can happen if daemon terminates while we're reading.
        if not self.response:
            return -1
        if self.verbose:
            sys.stderr.write("poll: data is %s\n" % repr(self.response))
        self.received = time.time()
        # We got a \n-terminated line
        return len(self.response)