Some augassign support

src/runtime/int.cpp

@@ -452,7 +452,7 @@ extern "C" Box* mod_i64_i64(i64 lhs, i64 rhs) {
 extern "C" Box* pow_i64_i64(i64 lhs, i64 rhs, Box* mod) {
     if (mod != None) {
         if (!PyInt_Check(mod)) {
-            return NotImplemented;
+            return incref(NotImplemented);
         }
         BoxedInt* mod_int = static_cast<BoxedInt*>(mod);
         if (mod_int->n == 0) {

src/runtime/long.cpp

@@ -1003,14 +1003,14 @@ static PyObject* long_richcompare(Box* _v1, Box* _v2, int op) noexcept {
 
 Box* convertToLong(Box* val) {
     if (PyLong_Check(val)) {
-        return val;
+        return incref(val);
     } else if (PyInt_Check(val)) {
         BoxedInt* val_int = static_cast<BoxedInt*>(val);
         BoxedLong* r = new BoxedLong();
         mpz_init_set_si(r->n, val_int->n);
         return r;
     } else {
-        return NotImplemented;
+        return incref(NotImplemented);
     }
 }
 

src/runtime/objmodel.cpp

@@ -4956,7 +4956,6 @@ Box* binopInternal(Box* lhs, Box* rhs, int op_type, bool inplace, BinopRewriteAr
 
     Box* irtn = NULL;
     if (inplace) {
-        assert(0 && "check refcounting");
         // XXX I think we need to make sure that we keep these strings alive?
         DecrefHandle<BoxedString> iop_name(getInplaceOpName(op_type));
         if (rewrite_args) {
@@ -4990,6 +4989,7 @@ Box* binopInternal(Box* lhs, Box* rhs, int op_type, bool inplace, BinopRewriteAr
                 }
                 return irtn;
             } else {
+                Py_DECREF(irtn);
                 assert(!rewrite_args);
             }
         }