[yocto] Change in override behavior?

[Gary Thomas]

I used to be able to use something like this:
   VARIABLE = "xyz"
and maybe in a .bbappend use
   VARIABLE_mymachine = "xyzzy"
where 'mymachine' is in OVERRIDES, which resulted in
   VARIABLE = "xyzzy"

This doesn't seem to work the same today, what I get is
   VARIABLE = "xyz"
   VARIABLE_mymachine = "xyzzy"

Has this changed (recently)?  Why?  How to I make use of overrides?

Note: I'm using the latest Poky master (a9b503b26) updated 2016-04-28

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------