Merge #177: fix checking on p2sh-p2wsh

96dd697 fix checking on p2sh-p2wsh (Wan Wenli)

Pull request description:

  After discussing in [this issue](#176), I think it is better to keep the methods signatures, but change the comments and fix a potential bug.

Top commit has no ACKs.

Tree-SHA512: 4f09f111903280d68a33394f64e02943bf9bdf287ec4bac470c5efabb334baddd3202b5e0fbad1ab4c9ccaca9325580d38881c60285a1adbc827281273ac1dc1

Author: petertodd

bitcoin/core/script.py

@@ -705,16 +705,16 @@ def is_witness_v0_keyhash(self):
         return len(self) == 22 and self[0:2] == b'\x00\x14'
 
     def is_witness_v0_nested_keyhash(self):
-        """Returns true if this is a scriptpubkey for V0 P2WPKH embedded in P2SH. """
+        """Returns true if this is a scriptSig for V0 P2WPKH embedded in P2SH. """
         return len(self) == 23 and self[0:3] == b'\x16\x00\x14'
 
     def is_witness_v0_scripthash(self):
         """Returns true if this is a scriptpubkey for V0 P2WSH. """
         return len(self) == 34 and self[0:2] == b'\x00\x20'
 
     def is_witness_v0_nested_scripthash(self):
-        """Returns true if this is a scriptpubkey for V0 P2WSH embedded in P2SH. """
-        return len(self) == 23 and self[0:2] == b'\xa9\x14' and self[-1] == b'\x87'
+        """Returns true if this is a scriptSig for V0 P2WSH embedded in P2SH. """
+        return len(self) == 35 and self[0:3] == b'\x22\x00\x20'
 
     def is_push_only(self):
         """Test if the script only contains pushdata ops