uucore: write error message leaks '(os error N)' where GNU does not

[sylvestre]

Write errors coming from the format machinery keep Rust's (os error N) suffix, which GNU does
not print:

$ printf 'foo\n' > /dev/full
printf: write error: No space left on device (os error 28)

$ /usr/bin/printf 'foo\n' > /dev/full
printf: write error: No space left on device

Both exit 1, so only the message differs.

Where

src/uucore/src/lib/features/format/mod.rs:116

Self::IoError(e) => write!(f, "write error: {e}"),

uucore::error::strip_errno exists for exactly this and is already used elsewhere, e.g.
src/uucore/src/lib/features/perms.rs and src/uucore/src/lib/features/checksum/mod.rs, both of
which format the same message as "{}: {}", translate!("common-write-error"), strip_errno(..).

Note on reproducing

The trailing newline matters: it makes the line-buffered stdout flush inside the format code,
which is the path that produces this message. printf 'foo' > /dev/full (no newline) fails
later, on the flush at exit, and takes a different code path with a correct message.

Why this is a good first issue

One-line change plus a regression test in tests/by-util/test_printf.rs, and it makes the output
match GNU exactly. Worth a quick grep for other spots that interpolate an io::Error directly
into a user-facing message.

Found with coreutils 0.10.0 (multi-call binary) at 282b8b4, compared against GNU coreutils
9.11.64.

[floze-the-genius]

I would like to work on this. I will use the existing uucore::error::strip_errno helper at the format IoError display boundary and add a Unix printf regression that writes a newline to /dev/full, asserting the exact stderr and exit status. I will also check adjacent format error displays for the same direct io::Error interpolation, without reading or copying GNU source.

[oech3]

I think this is something Rust std should care about. However, Rust's recommendation is keeping errno: rust-lang/rust#113132