Explicitly check Points against None

sapling_generators.py

@@ -23,7 +23,7 @@ def group_hash(D, M):
     digest.update(URS)
     digest.update(M)
     p = Point.from_bytes(digest.digest())
-    if not p:
+    if p is None:
         return None
     q = p * JUBJUB_COFACTOR
     if q == Point.ZERO:
@@ -34,7 +34,7 @@ def find_group_hash(D, M):
     i = 0
     while True:
         p = group_hash(D, M + bytes([i]))
-        if p:
+        if p is not None:
             return p
         i += 1
         assert i < 256

sapling_jubjub.py

@@ -147,7 +147,7 @@ class Point(object):
         while True:
             data = rand.b(32)
             p = Point.from_bytes(data)
-            if p:
+            if p is not None:
                 return p
 
     @staticmethod
@@ -164,7 +164,7 @@ class Point(object):
         u2 = (vv - Fq.ONE) / (vv * JUBJUB_D - JUBJUB_A)
 
         u = u2.sqrt()
-        if not u:
+        if u is None:
             return None
 
         if u.s % 2 != u_sign: