Merge #282: Fix another usage of openssl's ripemd160

f894632 Fix another usage of openssl's ripemd160 (Pablo Greco)

Pull request description:

Top commit has no ACKs.

Tree-SHA512: f1609522105b5727a59961b788eeddb9b1d69bb6f23f0c1dfabf764f4b41bf4c98d7e4f0f605374fefe11137ed1432ce077d2b07bdded9a82f7431290832dea2

bitcoin/core/scripteval.py

@@ -23,6 +23,7 @@
 import bitcoin.core._bignum
 import bitcoin.core.key
 import bitcoin.core.serialize
+from bitcoin.core.contrib.ripemd160 import ripemd160
 
 # Importing everything for simplicity; note that we use __all__ at the end so
 # we're not exporting the whole contents of the script module.
@@ -624,9 +625,7 @@ def check_args(n):
             elif sop == OP_RIPEMD160:
                 check_args(1)
 
-                h = hashlib.new('ripemd160')
-                h.update(stack.pop())
-                stack.append(h.digest())
+                stack.append(ripemd160(stack.pop()))
 
             elif sop == OP_ROT:
                 check_args(3)