fixes Bug 938346 - attachment flag labeling doesn't ignore obsolete atta...

...chments

this bug is annoying and only took 5 minutes to fix.  here's the before:
![scrumbugz_bug_938346_before](https://f.cloud.github.com/assets/5017470/1542675/30b3b3dc-4d4a-11e3-831a-108436ea05c8.png)
and the after:
![scrumbugz_bug_938346_after](https://f.cloud.github.com/assets/5017470/1542678/37d4c21e-4d4a-11e3-8a90-0f78a003b3a6.png)