Weird bug with fuel pipes.

[magnemoe]

Well this bug took a long time to figure out and Eve on the test save is littered now.

Eve exit rocket and an rover, rover has its on heat shield and deorbit rocket. 
The huge double layered plate is that I call an drag plate who add drag to the rear while still be able to use the rocket for adjustment. 
Rocket is small but uses an The Martian crew style crew cabin as in an chair inside an fairing. 
Used this in KSP 1.45 and only change is that rover will deorbit first and rocket will land afterward close to end point.  

However the clever trick who caused the bug is the long fuel pipe from the 360 fuel tank below the drag plate up to core stage of rocket. 
This let me use use core tank and the two boosters who is cross feed to core as fuel storage for the burn to Eve and into orbit. 
Before deorbiting I would jettison the decopler breaking the pipe so it would just use its small tank for deorbit. 

But in 1.73 this breaks fuel flow, even if crossfeed is with piping from boosters to core the core was drained first. Enabling cross feed and setting tank priority let the cores to be drawn first but the bosters would start draw fuel from the core once they was drawn dry. 
This happened even if the piping was broken as the first staging as I just hyperedit craft into Eve orbit. 

Yes nowday you can use fuel flow priority but fuel can not flow over the grinder and the plates. Its an hole for the pipe to pass trough. 
Has to use manual transfer.