Fix a bug in list.__index__

I think this exists on master as well.

src/runtime/builtin_modules/builtins.cpp

@@ -585,9 +585,9 @@ Box* getattrFuncInternal(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args,
     _str = coerceUnicodeToStr<S>(_str);
     if (S == CAPI && !_str)
         return NULL;
-    AUTO_DECREF(_str);
 
     if (!PyString_Check(_str)) {
+        Py_DECREF(_str);
         if (S == CAPI) {
             PyErr_SetString(TypeError, "getattr(): attribute name must be string");
             return NULL;
@@ -598,6 +598,7 @@ Box* getattrFuncInternal(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args,
     BoxedString* str = static_cast<BoxedString*>(_str);
     if (!PyString_CHECK_INTERNED(str))
         internStringMortalInplace(str);
+    AUTO_DECREF(str);
 
     Box* rtn;
     RewriterVar* r_rtn;
@@ -717,9 +718,9 @@ Box* hasattrFuncInternal(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args,
     _str = coerceUnicodeToStr<S>(_str);
     if (S == CAPI && !_str)
         return NULL;
-    AUTO_DECREF(_str);
 
     if (!PyString_Check(_str)) {
+        Py_DECREF(_str);
         if (S == CAPI) {
             PyErr_SetString(TypeError, "hasattr(): attribute name must be string");
             return NULL;
@@ -729,7 +730,6 @@ Box* hasattrFuncInternal(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args,
 
     BoxedString* str = static_cast<BoxedString*>(_str);
 
-    Py_INCREF(str);
     if (!PyString_CHECK_INTERNED(str))
         internStringMortalInplace(str);
     AUTO_DECREF(str);

src/runtime/list.cpp

@@ -1105,6 +1105,7 @@ Box* listIndex(BoxedList* self, Box* elt, Box* _start, Box** args) {
         if (stop < 0)
             stop = 0;
     }
+    stop = std::min(stop, self->size);
 
     for (int64_t i = start; i < stop; i++) {
         Box* e = self->elts->elts[i];

test/tests/list.py

-# expected: reffail
 l = range(5)
 print l
 print l * 5
@@ -237,4 +236,11 @@ try:
 except TypeError as e:
     print(type(e))
 
-print range(5).index(10, 100L, 200L)
+try:
+    print range(5).index(10, 100L, 200L)
+except Exception as e:
+    print e
+try:
+    print range(5).index(10, 100, 200)
+except Exception as e:
+    print e