SF patch 1547796 by Georg Brandl -- set literals.
diff --git a/Python/ceval.c b/Python/ceval.c
index 95def9a..25e6a0b 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1945,6 +1945,24 @@
 			}
 			break;
 
+		case BUILD_SET:
+			x = PySet_New(NULL);
+			if (x != NULL) {
+				for (; --oparg >= 0;) {
+					w = POP();
+					if (err == 0)
+						err = PySet_Add(x, w);
+					Py_DECREF(w);
+				}
+				if (err != 0) {
+					Py_DECREF(x);
+					break;
+				}
+				PUSH(x);
+				continue;
+			}
+			break;
+
 		case BUILD_MAP:
 			x = PyDict_New();
 			PUSH(x);