"Mending Fences" involves putting them back up, making them bigger and stronger.
As in "Good Fences Make Good Neighbors".
I've seen several references recently to "mending fences". I suspect what these fools mean is "mending bridges".
Myself, I'm for "mending fences".
It takes years to make a friendship. They destroyed it in a vote. Now is fence time where we can keep an eye on our enemies.