nested_except_trace: document about another problem

my2to3/fixes/fix_nested_except_trace.py

@@ -11,7 +11,7 @@ class FixNestedExceptTrace(BaseFix):
   """This fixer detects scope bugs which can occur due to nested except clauses
   which use the same variable name.
 
-  Try the following code yourself in Python 2 and Python 3...
+  Try the following two snippets yourself in Python 2 and Python 3...
 
   try:
     raise Exception("foo")
@@ -21,6 +21,17 @@ class FixNestedExceptTrace(BaseFix):
     except Exception as e:
       print(e)
     print(e)
+
+  ---
+
+  try:
+    raise Exception("foo")
+  except Exception as e:
+    try:
+      raise Exception("bar")
+    except Exception as e:
+      print(e)
+    raise
   """
   # https://github.com/python/cpython/blob/3549ca313a6103a3adb281ef3a849298b7d7f72c/Lib/lib2to3/fixes/fix_except.py#L39-L45
   PATTERN = """