rpc: Quote user supplied strings in error messages

test/functional/rpc_blockchain.py

@@ -329,7 +329,7 @@ class BlockchainTest(BitcoinTestFramework):
             assert 'muhash' not in r
 
         # Unknown hash_type raises an error
-        assert_raises_rpc_error(-8, "foohash is not a valid hash_type", node.gettxoutsetinfo, "foohash")
+        assert_raises_rpc_error(-8, "'foo hash' is not a valid hash_type", node.gettxoutsetinfo, "foo hash")
 
     def _test_getblockheader(self):
         self.log.info("Test getblockheader")