Running nargo compile in a package within a workspace doesn't write to the workspace target directory

[TomAFrench]

Consider the workspace below with two packages a and b.

.
├── Nargo.toml
├── a
│   ├── Nargo.toml
│   ├── Prover.toml
│   └── src
│       └── main.nr
├── b
│   ├── Nargo.toml
│   ├── Prover.toml
│   └── src
│      └── main.nr
└── target

If we run nargo compile from the workspace root then both a.json and b.json are written to the ./target directory at the workspace root. However if I cd into a and then run nargo compile then a.json will be written to a/target rather than ./target.

This is a confusing discrepancy, I would expect that we always write into the ./target directory.