types: fix formatting when printing signatures

- use cmn.Fingerprint and %X

types/proposal.go

@@ -4,6 +4,8 @@ import (
 	"errors"
 	"fmt"
 	"time"
+
+	cmn "github.com/tendermint/tendermint/libs/common"
 )
 
 var (
@@ -41,9 +43,10 @@ func NewProposal(height int64, round int, blockPartsHeader PartSetHeader, polRou
 
 // String returns a string representation of the Proposal.
 func (p *Proposal) String() string {
-	return fmt.Sprintf("Proposal{%v/%v %v (%v,%v) %v @ %s}",
+	return fmt.Sprintf("Proposal{%v/%v %v (%v,%v) %X @ %s}",
 		p.Height, p.Round, p.BlockPartsHeader, p.POLRound,
-		p.POLBlockID, p.Signature, CanonicalTime(p.Timestamp))
+		p.POLBlockID,
+		cmn.Fingerprint(p.Signature), CanonicalTime(p.Timestamp))
 }
 
 // SignBytes returns the Proposal bytes for signing