list-packets: raw data: unknown length

[feitao]

If the size of an encrypted file is large, say, 5G, --list-packets will show
"literal data packet: raw data: unknown length" and does not show any
information of the next packet (signature packet). Is this a bug? There must
be some way for gpg to tell the length of a packet.

:pubkey enc packet: version 3, algo 16, keyid xx
	data: [2047 bits]
	data: [2046 bits]
:encrypted data packet:
	length: unknown
	mdc_method: 2
:onepass_sig packet: keyid xx
	version 3, sigclass 00, digest 2, pubkey 17, last=1
:literal data packet:
	mode b (62), created 1145516298, name="xxxx",
	raw data: unknown length