Installing managed python with different mounts of .local and .cache fails.

[msw-kialo]

I have dedicated volumes mounted on ~/.cache and ~/.local: so uv fails to move files between them.
I know it is probably a rare setup, but I like having better control about these important directories.

> uv python install 3.12.4 --verbose
DEBUG uv 0.2.35
DEBUG Acquired lock for `~/.local/share/uv/python`
Searching for Python versions matching: Python 3.12.4
DEBUG Using request timeout of 30s
DEBUG Downloading https://github.com/indygreg/python-build-standalone/releases/download/20240726/cpython-3.12.4%2B20240726-x86_64-unknown-linux-gnu-install_only_stripped.tar.gz to temporary location: ~/.cache/uv/.tmpChAkwk
DEBUG Extracting cpython-3.12.4%2B20240726-x86_64-unknown-linux-gnu-install_only_stripped.tar.gz
DEBUG Moving ~/.cache/uv/.tmpChAkwk/python to ~/.local/share/uv/python/cpython-3.12.4-linux-x86_64-gnu
error: Failed to install cpython-3.12.4-linux-x86_64-gnu: Failed to copy to: ~/.local/share/uv/python/cpython-3.12.4-linux-x86_64-gnu

The error message of uv lock (in a project that requires installing python) is a bit more detailed:

> uv lock
error: Failed to copy to: ~/.local/share/uv/python/cpython-3.12.4-linux-x86_64-gnu
  Caused by: failed to rename file from ~/.cache/uv/.tmpUQC45r/python to ~/.local/share/uv/python/cpython-3.12.4-linux-x86_64-gnu
  Caused by: Invalid cross-device link (os error 18)

[charliermarsh]

Thanks for reporting -- we should definitely be robust to this.