pedersen_hash: adds tests for Daniel's vector

zcash_primitives/src/pedersen_hash.rs

@@ -5,6 +5,7 @@ use ff::{Field, PrimeField, PrimeFieldRepr};
 pub enum Personalization {
     NoteCommitment,
     MerkleTree(usize),
+    Empty,
 }
 
 impl Personalization {
@@ -16,6 +17,9 @@ impl Personalization {
 
                 (0..6).map(|i| (num >> i) & 1 == 1).collect()
             }
+            Personalization::Empty => {
+                vec![true, true, true, false, false, false]
+            }
         }
     }
 }