Comment 5 for bug 714904

Here are the steps necessary to correct the package files after apt-get install ifenslave-2.6 results in the observed state, this solution also corrects the above mentioned issue I observed regarding the preservation of mode across reboots without any changes using the approved hotplug method.

$ /etc/network $ find . -name "*enslave*"
./if-pre-up.d/ifenslave.dpkg-new
./if-pre-up.d/ifenslave
./if-post-down.d/ifenslave

To correct the package perform the following steps:

mv /etc/network/if-pre-up.d/ifenslave /etc/network/if-up.d/ifenslave
mv /etc/network/if-pre-up.d/ifenslave.dpkg-new /etc/network/if-pre-up.d/ifenslave

As Rob Hall correctly notes the source package script is confused, however, not because it ended up in the wrong place when it attempted to write /etc/network/if-pre-up.d/ifenslave, but because there is an existing file which in fact should be /etc/network/if-up.d/ifenslave.