Patch #1682205: a TypeError while unpacking an iterable is no longer

masked by a generic one with the message "unpack non-sequence".
 (backport from rev. 54480)

Lib/test/test_unpack.py

@@ -55,7 +55,7 @@ Unpacking non-sequence
     >>> a, b, c = 7
     Traceback (most recent call last):
       ...
-    TypeError: unpack non-sequence
+    TypeError: 'int' object is not iterable
 
 Unpacking tuple of wrong size
 

Misc/NEWS

@@ -12,6 +12,9 @@ What's New in Python 2.5.1c1?
 Core and builtins
 -----------------
 
+- Patch #1682205: a TypeError while unpacking an iterable is no longer
+  masked by a generic one with the message "unpack non-sequence".
+
 - Patch #1642547: Fix an error/crash when encountering syntax errors in
   complex if statements.
 

Python/ceval.c

@@ -1765,12 +1765,10 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
 					PUSH(w);
 				}
 			} else if (unpack_iterable(v, oparg,
-						 stack_pointer + oparg))
+						 stack_pointer + oparg)) {
 				stack_pointer += oparg;
-			else {
-				if (PyErr_ExceptionMatches(PyExc_TypeError))
-					PyErr_SetString(PyExc_TypeError,
-						"unpack non-sequence");
+			} else {
+				/* unpack_iterable() raised an exception */
 				why = WHY_EXCEPTION;
 			}
 			Py_DECREF(v);