Re: Packaging a python package that is using setuptools_rust

[Hamzeh Nasajpour]

Hi Hartmut,

> You could validate $PATH like this: Add a phase before the
> build-phase, containing just "(pk (getenv PATH))".

This is the output of this line:
```
/gnu/store/wc4xh9wj49rlbyivxi4lsws6whhzx4ab-python-wrapper-3.8.2/bin:/gnu/store/axjq514q8gqk90hi7r7wpfbba3id6h18-rust-1.39.0/bin:/gnu/store/v6f44zccwh9z5zk3pjlywjybbi8n2hjh-tar-1.32/bin:/gnu/store/ncydgq2znms5n1d2k5yqshhf58nsixwv-gzip-1.10/bin:/gnu/store/i8h2pcxqdq07ijm3ibkka8f4smn1w48v-bzip2-1.0.8/bin:/gnu/store/9860f1abqj8wjjnwl8a9v54pdcc3bhgf-xz-5.2.4/bin:/gnu/store/60g7r3l01fd7c58yjbm6krgcwj1jkpwg-file-5.38/bin:/gnu/store/n4n560pfvvw50a9369axw5vj5rrqfj1n-diffutils-3.7/bin:/gnu/store/cd5qf3kcnlq35p9k392pjdpdzpsnds70-patch-2.7.6/bin:/gnu/store/hic7snhayfl7m6cpfqqr73nmm19bpqkg-findutils-4.7.0/bin:/gnu/store/swqdvwri9dbv6zssg6v0by7l05hd6wxp-gawk-5.0.1/bin:/gnu/store/ishk7fswcs4gkwcp8mh788z4mvvl9bxh-sed-4.8/bin:/gnu/store/bhs4rj58v8j1narb2454raan2ps38xd8-grep-3.4/bin:/gnu/store/57xj5gcy1jbl9ai2lnrqnpr0dald9i65-coreutils-8.32/bin:/gnu/store/hm40bxnv8jxmbc1lpb7zfimii4xm9m81-make-4.3/bin:/gnu/store/pwcp239kjf7lnj5i4lkdzcfcxwcfyk72-bash-minimal-5.0.16/bin:/gnu/store/mpa04aq8lblbcviyxywxcsb1zbi0mf39-ld-wrapper-0/bin:/gnu/store/m1z7cdbqsqyp9xnjw5cvlb4a7gkcg3m4-binutils-2.34/bin:/gnu/store/rn75fm7adgx3pw5j8pg3bczfqq1y17lk-gcc-7.5.0/bin:/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/bin:/gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/sbin:/gnu/store/q9rm8h9imazsq2c4qiv2yjpvlvliywqb-python-3.8.2/bin
```

> /gnu/store/axjq514q8gqk90hi7r7wpfbba3id6h18-rust-1.39.0/bin

As you can see, the `rust` path is available in the `PATH`. I get the list of 
this path:
```
$ ls /gnu/store/axjq514q8gqk90hi7r7wpfbba3id6h18-rust-1.39.0/bin/
rustc  rustdoc  rust-gdb  rust-gdbgui  rust-lldb
```

I couldn't see the `cargo`. I also couldn't find any package for installing the 
`cargo`.


Regards,
Hamzeh