This bug was fixed in the package ifupdown - 0.7~beta2ubuntu3
---
ifupdown (0.7~beta2ubuntu3) precise; urgency=low
* More label fixes from upstream, don't bring down the parent
when bringing down a label.
http://anonscm.debian.org/hg/collab-maint/ifupdown/rev/f9cef973859e
Marking as low as the end behaviour with or without the fix is
identical, only the message printed to the user changes.
This will be fixed in the next Precise upload but as it doesn't actually
break anything in Ubuntu 11.10, I won't SRU it.
** Changed in: ifupdown (Ubuntu)
Importance: Undecide
