[PATCH] imagebuilder: add check if target is sourced from a feed

[Florian Eckert]

Hello Thomas

> I tested your patch, it works well.

Thanks

> But I don't know how you created your imagebuilder.
> On my side, building an imagebuilder for a target sourced from a feed
> didn't work.

I forgot to send a second commit that fixes this issue comprehensive.
Thanks for the reminder.

> So I just sent a patch to fix it:
> http://lists.openwrt.org/pipermail/openwrt-devel/2024-March/042452.html

Yours change looks exactly like my modification. So I don't care which 
one is used.
The main thing is that it is fixed.

I opened a pullrequest right now that include the fix that a had on my 
patch set [1] for a long time.
And also the patch I have already send to the mailing list [2].

Best regards

Florian

[1] https://github.com/openwrt/openwrt/pull/14937
[2] 
https://patchwork.ozlabs.org/project/openwrt/patch/20231020114527.3586387-1-fe@dev.tdt.de/