When wearing leather, studded leather or chainshirts with an innate +1 ac, the vagabond perk gives a lower ac pay-out than it should.
Some examples;
A level eight fighter with 14 dexterity wears the following:
A plain leather (2 ac); Receives +4 ac from the perk
A plain studded leather (3 ac); receives +3 from the perk
A plain chainshirt (4 ac); receives +2 from the perk
A +1 ac leather (2 base, 1 magical); receives +3 from the perk (and because this +3 does not stack with the +1, actually has one ac lower than they should)
A +1 ac studded leather (3 base, 1 magical); receives +2 from the perk (and because this +2 does not stack with the +1, actually has one ac lower than they should)
A +1 ac chainshirt (4 base, 1 magical); receives no ac from the perk
The perk should hand out ac bonus based on the base armour's ac output, not judge it based on the total ac a piece of armour gives. Because multiple ac increases do not stack. Having a permanent +1 ac on your armour does not stack with a temporary +3 one.
Can confirm the bug. Has been like that for a while.