Always try to sign for all pubkeys in multisig

Author: achow101

src/script/sign.cpp

@@ -144,8 +144,13 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
         ret.push_back(valtype()); // workaround CHECKMULTISIG bug
         for (size_t i = 1; i < vSolutions.size() - 1; ++i) {
             CPubKey pubkey = CPubKey(vSolutions[i]);
-            if (ret.size() < required + 1 && CreateSig(creator, sigdata, provider, sig, pubkey, scriptPubKey, sigversion)) {
-                ret.push_back(std::move(sig));
+            // We need to always call CreateSig in order to fill sigdata with all
+            // possible signatures that we can create. This will allow further PSBT
+            // processing to work as it needs all possible signature and pubkey pairs
+            if (CreateSig(creator, sigdata, provider, sig, pubkey, scriptPubKey, sigversion)) {
+                if (ret.size() < required + 1) {
+                    ret.push_back(std::move(sig));
+                }
             }
         }
         bool ok = ret.size() == required + 1;