git-subtree-dir: datalad_next/iterable_subprocess
git-subtree-split: 46343c074d2c062dd0822e60a86665b2cce2d93b

…ext/iterable_subprocess'

Source: https://github.com/uktrade/iterable-subprocess

It is not 100% clear to me whether this is correct, but
`OSError(errno22)` can and does occur when interacting with
file descriptors of dead processes.

That module imports too many components with too many dependency that
also needs (these) constants. This creates import loops.

The change established a toplevel `consts` module with minimal
dependencies. The legacy location is kept and a comment
warns against further use.

This is a convenience wrapper around `datalad_next.iterable_subprocess`.
The main purpose is to have a place for documentation and feature
additions -- without adding needless diff to the original implementation
that was merged in from an external source.

The wrapper uses `COPY_BUFSIZE` as default chunk size (which is
numerically identical to the hardcoded default on POSIX systems).
This should be better than a separate literal.

A second different is the option to run a subprocess without any
explicit input.

There is not really a point to compatibility with versions that
are nearing EOL

For now containers processors for byte-string iterables and
functionality related to subprocess output.