[hotfix] fix an emergent bug on updating validator account

Author: longzhi

modules/stake/handler.go

@@ -452,6 +452,11 @@ func (c check) updateCandidateAccount(tx TxUpdateCandidacyAccount, gasFee sdk.In
 		return 0, ErrBadRequest()
 	}
 
+	tmp := GetCandidateByAddress(tx.NewCandidateAddress)
+	if tmp != nil {
+		return 0, ErrBadRequest()
+	}
+
 	// check if the new address has been delegated the candidate
 	d := GetDelegation(tx.NewCandidateAddress, candidate.Id)
 	if d != nil {
@@ -484,6 +489,11 @@ func (c check) acceptCandidateAccountUpdateRequest(tx TxAcceptCandidacyAccountUp
 		return ErrBadRequest()
 	}
 
+	tmp := GetCandidateByAddress(req.ToAddress)
+	if tmp != nil {
+		return ErrBadRequest()
+	}
+
 	// check if the new address has been delegated the candidate
 	d := GetDelegation(req.ToAddress, req.CandidateId)
 	if d != nil {

version/version.go

@@ -7,7 +7,7 @@ import (
 const Major = "0"
 const Minor = "1"
 const Patch = "3"
-const Label = "beta-hotfix1"
+const Label = "beta-hotfix2"
 
 var (
 	// Version is the current version of Travis