Use the param type instead of the column type

Fixes #170

Author: Ronan Dunklau

src/python.c

@@ -932,7 +932,7 @@ execute(ForeignScanState *node, ExplainState *es)
 				newqual->base.isArray = qual->isArray;
 				newqual->base.useOr = qual->useOr;
 				newqual->value = ExecEvalExpr(expr_state, econtext, &isNull, NULL);
-				newqual->base.typeoid = qual->typeoid;
+				newqual->base.typeoid = ((Param*) ((MulticornParamQual *) qual)->expr)->paramtype;
 				newqual->isnull = isNull;
 				break;
 			case T_Const: