Address long-standing Python 2.6 try/except bug

Fixes #405

test/simple_source/bug26/07_try_except.py

@@ -0,0 +1,34 @@
+# Bug portion of Issue #405 https://github.com/rocky/python-uncompyle6/issues/405
+# Bug was detecting if/else as the last item in a "try: .. except" block.
+class Saveframe(object):
+    """A saveframe. Use the classmethod from_scratch to create one."""
+
+    frame_list = {}
+
+    def frame_dict(self):
+        return
+
+    # Next line is 1477
+    def __setitem__(self, key, item):
+        # Next line is 1481
+        if isinstance(item, Saveframe):
+            try:
+                self.frame_list[key] = item
+            except TypeError:
+                if key in (self.frame_dict()):
+                    dict((frame.name, frame) for frame in self.frame_list)
+                    for pos, frame in enumerate(self.frame_list):
+                        if frame.name == key:
+                            self.frame_list[pos] = item
+                else:
+                    raise KeyError(
+                        "Saveframe with name '%s' does not exist and "
+                        "therefore cannot be written to. Use the add_saveframe method to add new saveframes."
+                        % key
+                    )
+        # Next line is 1498
+        raise ValueError("You can only assign an entry to a saveframe splice.")
+
+
+x = Saveframe()
+x.__setitem__("foo", 5)