[OE-core] [OE-Core][PATCH] {python, python3}-native: fix TypeError

[Richard Purdie]

On Tue, 2015-06-16 at 14:33 +0900, Changhyeok Bae wrote:
> Doesn't this mean BUILD_SYS or HOST_SYS weren't set in the environment?
> -> You're right. The default env value of BUILD_SYS and HOST_SYS is "" (empty).
> -> I wonder that the original patch (12-distutils-prefix-is-inside-staging-area.patch) to add  is required?
> 
> Wouldn't this patch just mean you get a value of something like "None"?
> -> My patch is to prevent errors in runtime.
> -> Do you have any other good idea?

My concern is that just having a value of "None" means the code trying
to use this variable will probably do the wrong thing. We should try and
fix the underlying problem of BUILD_SYS bot being set when it should be,
rather than just hide the runtime error.

How you do that depends on when the runtime error is occurring which I
know little about...

Cheers,

Richard