[oe] Best practise using .bbappend

[Alex J Lennon]

Hi Paul,

 >approach assuming this is a layer intended to apply some policy (i.e. 
a distro layer).

Good to know. I'm currently working with most of this in local.conf but
my plan is to migrate it to a distro configuration when I've figured out 
what I'm
doing, yes.

 >In practice this is unlikely to come up too often - in OE-Core we 
usually delete the old recipe when upgrading to a new version, and thus 
if you have a bbappend for the old version in your layer you will get an 
error after parsing indicating the bbappend had no matching recipe.

Ah very good. So if I update from the git repo and a recipe I've 
extended has changed
I would get a build error rather than it silently dropping my changes. 
Good :)

Many thanks,

Alex