diff -r 2f86a69c3220 Objects/setobject.c
--- a/Objects/setobject.c	Tue Jul 07 00:34:37 2015 -0500
+++ b/Objects/setobject.c	Tue Jul 07 11:37:36 2015 +0300
@@ -1249,12 +1249,8 @@ set_intersection(PySetObject *so, PyObje
             key = entry->key;
             hash = entry->hash;
             rv = set_contains_entry(so, key, hash);
-            if (rv < 0) {
-                Py_DECREF(result);
-                return NULL;
-            }
-            if (rv) {
-                if (set_add_entry(result, key, hash)) {
+            if (rv != 0) {
+                if (rv < 0 || set_add_entry(result, key, hash)) {
                     Py_DECREF(result);
                     return NULL;
                 }
@@ -1274,10 +1270,8 @@ set_intersection(PySetObject *so, PyObje
         if (hash == -1)
             goto error;
         rv = set_contains_entry(so, key, hash);
-        if (rv < 0)
-            goto error;
-        if (rv) {
-            if (set_add_entry(result, key, hash))
+        if (rv != 0) {
+            if (rv < 0 || set_add_entry(result, key, hash))
                 goto error;
         }
         Py_DECREF(key);
@@ -1399,10 +1393,11 @@ set_isdisjoint(PySetObject *so, PyObject
         }
         while (set_next((PySetObject *)other, &pos, &entry)) {
             rv = set_contains_entry(so, entry->key, entry->hash);
-            if (rv < 0)
-                return NULL;
-            if (rv)
+            if (rv != 0) {
+                if (rv < 0)
+                    return NULL;
                 Py_RETURN_FALSE;
+            }
         }
         Py_RETURN_TRUE;
     }
@@ -1421,12 +1416,10 @@ set_isdisjoint(PySetObject *so, PyObject
         }
         rv = set_contains_entry(so, key, hash);
         Py_DECREF(key);
-        if (rv < 0) {
+        if (rv != 0) {
             Py_DECREF(it);
-            return NULL;
-        }
-        if (rv) {
-            Py_DECREF(it);
+            if (rv < 0)
+                return NULL;
             Py_RETURN_FALSE;
         }
     }
@@ -1535,12 +1528,8 @@ set_difference(PySetObject *so, PyObject
             key = entry->key;
             hash = entry->hash;
             rv = _PyDict_Contains(other, key, hash);
-            if (rv < 0) {
-                Py_DECREF(result);
-                return NULL;
-            }
-            if (!rv) {
-                if (set_add_entry((PySetObject *)result, key, hash)) {
+            if (rv <= 0) {
+                if (rv < 0 || set_add_entry((PySetObject *)result, key, hash)) {
                     Py_DECREF(result);
                     return NULL;
                 }
@@ -1554,12 +1543,8 @@ set_difference(PySetObject *so, PyObject
         key = entry->key;
         hash = entry->hash;
         rv = set_contains_entry((PySetObject *)other, key, hash);
-        if (rv < 0) {
-            Py_DECREF(result);
-            return NULL;
-        }
-        if (!rv) {
-            if (set_add_entry((PySetObject *)result, key, hash)) {
+        if (rv <= 0) {
+            if (rv < 0 || set_add_entry((PySetObject *)result, key, hash)) {
                 Py_DECREF(result);
                 return NULL;
             }
@@ -1633,12 +1618,8 @@ set_symmetric_difference_update(PySetObj
         while (_PyDict_Next(other, &pos, &key, &value, &hash)) {
             Py_INCREF(key);
             rv = set_discard_entry(so, key, hash);
-            if (rv < 0) {
-                Py_DECREF(key);
-                return NULL;
-            }
-            if (rv == DISCARD_NOTFOUND) {
-                if (set_add_entry(so, key, hash)) {
+            if (rv <= 0) {
+                if (rv < 0 || set_add_entry(so, key, hash)) {
                     Py_DECREF(key);
                     return NULL;
                 }
@@ -1661,12 +1642,8 @@ set_symmetric_difference_update(PySetObj
         key = entry->key;
         hash = entry->hash;
         rv = set_discard_entry(so, key, hash);
-        if (rv < 0) {
-            Py_DECREF(otherset);
-            return NULL;
-        }
-        if (rv == DISCARD_NOTFOUND) {
-            if (set_add_entry(so, key, hash)) {
+        if (rv <= 0) {
+            if (rv < 0 || set_add_entry(so, key, hash)) {
                 Py_DECREF(otherset);
                 return NULL;
             }
@@ -1744,10 +1721,11 @@ set_issubset(PySetObject *so, PyObject *
 
     while (set_next(so, &pos, &entry)) {
         rv = set_contains_entry((PySetObject *)other, entry->key, entry->hash);
-        if (rv < 0)
-            return NULL;
-        if (!rv)
+        if (rv <= 0) {
+            if (rv < 0)
+                return NULL;
             Py_RETURN_FALSE;
+        }
     }
     Py_RETURN_TRUE;
 }