cannot reference target in another directory when directory is defined in LET or ENV

[idodod]

What went wrong?

I have 2 target each in a separate Earthfiles. when one target calls the other and specifying the path of the Earthfile where the called target is via LET or ENV, the build fails. When specifying the path via an ARG, the build succeeds.

.
├── Earthfile
└── subdir
    └── Earthfile

./Earthfile:

VERSION 0.8

FROM alpine


caller-with-let:
    LET path="subdir"
    BUILD ./$path+called

caller-with-arg:
    ARG path="subdir"
    BUILD ./$path+called

caller-with-env:
    ENV path="subdir"
    BUILD ./$path+called

./subdir/Earthfile

VERSION 0.8

called:
    FROM alpine
    RUN --no-cache echo called target successfully

earthly +caller-with-let - fails
earthly +caller-with-env - fails
caller-with-arg - succeeds

When it fails, it displays an error such as:

  Error: async earthfile2llb for ./+called: Earthfile line 0:0 target called not found
     18  in             +called

What should have happened?

Other Helpful Information

https://cloud.earthly.dev/builds/9a343710-c326-4fb9-a842-6718a6156de2