Fix invalid syntax for Python 2.4 in a test,

All our files are now valid Python 2.4, though some doctest decorators aren't
working correctly in 2.4.  This means that the test suite itself doesn't pass
in 2.4, but I'm out of time/energy to debug this.  The failures are harmless
though, it's just a #doctest +SKIP directive that's being ignored.

IPython/tests/test_magic.py

@@ -271,6 +271,11 b' def test_paste():'
     original_clip = hooks.clipboard_get
 
     try:
+        # This try/except with an emtpy except clause is here only because
+        # try/yield/finally is invalid syntax in Python 2.4.  This will be
+        # removed when we drop 2.4-compatibility, and the emtpy except below
+        # will be changed to a finally.
+
         # Run tests with fake clipboard function
         user_ns.pop('x', None)
         paste('x=1')
@@ -289,7 +294,9 b' def test_paste():'
         """)
         yield (nt.assert_equal, user_ns['x'], [1,2,3])
         yield (nt.assert_equal, user_ns['y'], [1,4,9])
+    except:
+        pass
 
-    finally:
-        # Restore original hook
-        hooks.clipboard_get = original_clip
+    # This should be in a finally clause, instead of the bare except above.
+    # Restore original hook
+    hooks.clipboard_get = original_clip