Also struggling with something similar, I thought I hit this bug, but actually no. Let me bring more details.
> arch-test looks for its test files *inside* the chroot;
That's not how I read the code. It copies the helper in the chroot, and then it runs it with chroot:
https://github.com/kilobyte/arch-test/blob/28f25fef25cdb09805a20986414bf3435c67d47f/arch-test#L56
And here's a corresponding trace, while running it with '-x':
+ exit 1
Cheers,
Arnaud