Add check for scriptSig in ConsensusVerifyScript

scriptSig is redundant there, but is retained for compatibilty
with VerifyScript(). But it cannot be ignored, and therefore it
is now checked to be the same as the scriptSig in the input.

Author: dgpv

bitcointx/core/bitcoinconsensus.py

@@ -194,7 +194,10 @@ def ConsensusVerifyScript(
     The arguments are compatible with `VerifyScript()` from
     `bitcointx.core.scripteval`
 
-    scriptSig    - Signature
+    scriptSig    - Signature. Must be present in the transaction input at
+                   inIdx. Redundant, but is there for compatibility of
+                   arguments with VerifyScript() that allow to supply
+                   different scriptSig than the one in the input
     scriptPubKey - PubKey
     txTo         - Spending transaction
     inIdx        - Index of the transaction input containing scriptSig
@@ -223,6 +226,16 @@ def ConsensusVerifyScript(
     if not MoneyRange(amount):
         raise ValueError('amount out of MoneyRange')
 
+    ensure_isinstance(scriptSig, CScript, 'scriptSig')
+    if not type(scriptSig) == type(scriptPubKey):
+        raise TypeError(
+            "scriptSig and scriptPubKey must be of the same script class")
+
+    if txTo.vin[inIdx].scriptSig != scriptSig:
+        raise ValueError(
+            f'supplied scriptSig is not present in input {inIdx} of '
+            f'the supplied transaction')
+
     if witness is not None:
         ensure_isinstance(witness, CScriptWitness, 'witness')
         if not txTo.wit.vtxinwit[inIdx].scriptWitness.is_null() \