It should be noted that the new "Avoid-this-planet" feature doesn't actually work.
In my current game, I created an "avoid flag" in the CTRLS on the planet "Achtoothsuo".
My units are on Yoslovtch, trying to get to Charquta.
Now when you select the units on Yoslovtch, and give them a path to Charquta, interestingly the path avoids Achtoothsuo, and takes them through the neutered planet of Shloafr instead. However, when the units actually start GOING, they just ignore the path the game says they will take, and they just go to Achtoothsuo anyway.
TL;DR - Achtoothsuo is marked as a "NO GO". Take the units on Yoslovtch, and tell them to go to Charquta. See what happens.