Despite https://github.com/istio/istio/wiki/Vendor-FAQ#how-do-i-add--change-a-dependency

The vendor changes are more error prone and painful than they should be

There are a couple of distinct issues

• The fundamental one - which wouldn't go away in any setup I can think of, is vendor changes are intrinsically serialized / not mergeable (though they could be mostly mergeable - or we could automate the merging, and recalculation of go dep's input sha)

• Pruning is a good thing but also means anything not in use is deleted, before it can be used.

• Istio API changes should be automatically tracked (and fortio's too while at it)

• Contributors need to make a branch in vendor-istio which they can't do by default (only core contributors can) - I have been adding people one by one but that's not scaleable

I'm quite tempted to throw the towel at the coming end of my 2months warranty period and let people check in directly into istio/istio

cc @jwendell @ZackButcher @sebastienvas @hklai