Merge #11483: Fix importmulti bug when importing an already imported key

a44a21517 Fix importmulti bug when importing an already imported key (Pedro Branco)

Pull request description:

  This PR fixes a bug in `importmulti` RPC call where it returns an invalid response when importing an already imported key.

  Before:
  ```sh
  ❯ bitcoin-cli -regtest importmulti '[{ "keys": ["cNcMUunXhVK1dXJ5riixtpYSxPXZnUAMGS4vpzwChdKmYY3Rz99v"], "scriptPubKey": { "address": "n4YZAf4WE2XF3t4BfeYS2nHAhb8CVx91BR" }, "timestamp": 1507655239 }]'
  [{ "success": true }]

  ❯ bitcoin-cli -regtest importmulti '[{ "keys": ["cNcMUunXhVK1dXJ5riixtpYSxPXZnUAMGS4vpzwChdKmYY3Rz99v"], "scriptPubKey": { "address": "n4YZAf4WE2XF3t4BfeYS2nHAhb8CVx91BR" }, "timestamp": 1507655239 }]' '{ "rescan": false }'
  [ false ]

  ❯ bitcoin-cli -regtest importmulti '[{ "keys": ["cNcMUunXhVK1dXJ5riixtpYSxPXZnUAMGS4vpzwChdKmYY3Rz99v"], "scriptPubKey": { "address": "n4YZAf4WE2XF3t4BfeYS2nHAhb8CVx91BR" }, "timestamp": 1507655239 }]' '{ "rescan": true }'
  error code: -1
  error message:
  JSON value is not a boolean as expected
  ```

  After this fix:
  ```sh
  ❯ bitcoin-cli -rpcuser=u -rpcpassword=p -regtest importmulti '[{ "keys": ["cNcMUunXhVK1dXJ5riixtpYSxPXZnUAMGS4vpzwChdKmYY3Rz99v"], "scriptPubKey": { "address": "n4YZAf4WE2XF3t4BfeYS2nHAhb8CVx91BR" }, "timestamp": 1507655139 }]'
  [{ "success": true }]

  ❯ bitcoin-cli -rpcuser=u -rpcpassword=p -regtest importmulti '[{ "keys": ["cNcMUunXhVK1dXJ5riixtpYSxPXZnUAMGS4vpzwChdKmYY3Rz99v"], "scriptPubKey": { "address": "n4YZAf4WE2XF3t4BfeYS2nHAhb8CVx91BR" }, "timestamp": 1507655139 }]'
  [{ "success": false, "error": { "code": -4, "message": "The wallet already contains the private key for this address or script" } }]
  ```

Tree-SHA512: 4acebdfb7d0ebd7cd48e943b93ed1cec072db1ace5c42b3f5cc225603764b6e804e4b823b0710965826aafc2f0c615c53d5aefcfdb9bc9c379f5221b798a318c

src/wallet/rpcdump.cpp

@@ -961,7 +961,7 @@ UniValue ProcessImport(CWallet * const pwallet, const UniValue& data, const int6
                 pwallet->SetAddressBook(vchAddress, label, "receive");
 
                 if (pwallet->HaveKey(vchAddress)) {
-                    return false;
+                    throw JSONRPCError(RPC_WALLET_ERROR, "The wallet already contains the private key for this address or script");
                 }
 
                 pwallet->mapKeyMetadata[vchAddress].nCreateTime = timestamp;

test/functional/importmulti.py

@@ -160,6 +160,18 @@ class ImportMultiTest (BitcoinTestFramework):
         assert_equal(address_assert['ismine'], True)
         assert_equal(address_assert['timestamp'], timestamp)
 
+        self.log.info("Should not import an address with private key if is already imported")
+        result = self.nodes[1].importmulti([{
+            "scriptPubKey": {
+                "address": address['address']
+            },
+            "timestamp": "now",
+            "keys": [ self.nodes[0].dumpprivkey(address['address']) ]
+        }])
+        assert_equal(result[0]['success'], False)
+        assert_equal(result[0]['error']['code'], -4)
+        assert_equal(result[0]['error']['message'], 'The wallet already contains the private key for this address or script')
+
         # Address + Private key + watchonly
         self.log.info("Should not import an address with private key and with watchonly")
         address = self.nodes[0].validateaddress(self.nodes[0].getnewaddress())