[Pkg-rust-maintainers] Upcoming switches to zlib-rs

[Josh Triplett]

[Ccing Folkert, one of the upstream maintainers of zlib-rs.]

Several upstream Rust crates are switching to zlib-rs, including cargo,
rustup, and gitoxide. I wanted to give you as much advance notice as
possible, since it looks like zlib-rs isn't packaged in Debian yet. (I'd
expect it to be relatively easy to package; it shouldn't have any
unusual requirements compared to other Rust crates.) This will also
require flate2 1.1.1.

This came about because zlib-rs 0.5.0 made a change to no longer export
the C zlib symbols by default, so using zlib-rs no longer requires
carefully making sure that nothing else in the address space uses a
different zlib library; there won't be any symbol conflicts.

I would not expect this to become an issue until after the upcoming
stable release. (It'll come up for new versions of rustc-web, though.)

Hopefully this will go smoothly; please reach out if there are any
issues.

- Josh Triplett