channeldb: revocation hashes are 20 bytes

* Although, why not 32?

channeldb/channel.go

@@ -78,7 +78,7 @@ type OpenChannel struct {
 	// Current revocation for their commitment transaction. However, since
 	// this is the hash, and not the pre-image, we can't yet verify that
 	// it's actually in the chain.
-	TheirCurrentRevocation [wire.HashSize]byte
+	TheirCurrentRevocation [20]byte
 	TheirShaChain          *shachain.HyperShaChain
 	OurShaChain            *shachain.HyperShaChain
 

channeldb/channel_test.go

@@ -31,6 +31,11 @@ var (
 		0x2d, 0xe7, 0x93, 0xe4, 0xb7, 0x25, 0xb8, 0x4d,
 		0x1f, 0xb, 0x4c, 0xf9, 0x9e, 0xc5, 0x8c, 0xe9,
 	}
+	rev = [20]byte{
+		0x51, 0xb6, 0x37, 0xd8, 0xfc, 0xd2, 0xc6, 0xda,
+		0x48, 0x59, 0xe6, 0x96, 0x31, 0x13, 0xa1, 0x17,
+		0x2d, 0xe7, 0x93, 0xe4,
+	}
 	testTx = &wire.MsgTx{
 		Version: 1,
 		TxIn: []*wire.TxIn{
@@ -146,7 +151,7 @@ func TestOpenChannelEncodeDecode(t *testing.T) {
 		FundingTx:              testTx,
 		MultiSigKey:            privKey,
 		FundingRedeemScript:    script,
-		TheirCurrentRevocation: id,
+		TheirCurrentRevocation: rev,
 		OurDeliveryAddress:     addr,
 		TheirDeliveryAddress:   addr,
 		CsvDelay:               5,