No directive that I know of.
The jacket Moelders is wearing is most likely "private purchase", something he had made up. You will also see him wearing private purchase fur gloves in some photos. There were many Luftwaffe pilots that did the same. This was common during the early part of the war when the Luftwaffe had a somewhat limited selection of "production" flight gear. You can see numerous early war pictures of Luftwaffe pilots wearing what look like leather motorcycle jackets purchased in France.
IIRC Heinz Bar traded something with a crew member for the AAF A-2 jacket.
