Obviously, with a mending pickaxe, your XP will be consumed to repair the pickaxe, so you don't gain 100% xp you get unless your pickaxe is at full durability; I think if the pickaxe isn't at a bad durability, like 90%, you'll even get some xp.
The other bug report that you've said doesn't say anything about b.
Tiago Lobo Ferreira
Obviously, with a mending pickaxe, your XP will be consumed to repair the pickaxe, so you don't gain 100% xp you get unless your pickaxe is at full durability; I think if the pickaxe isn't at a bad durability, like 90%, you'll even get some xp.