Advancements execute rewards before printing message in chat

The bug

An advancement will print a message in chat only after all rewards have been executed. This means if you have a function granting the player a second advancement, the order would be reversed. Another example is where the map gives the player extra information after completing the advancement. This would all be printed above the advancement message "Player has made the advancement [...]"

How to reproduce

1. Make an advancement which calls a function as reward
2. Put a /say command in that function
3. Grant that advancement to yourself
   → Notice the /say message is printed in chat before the advancement prints "Player has made the advancement [...]"