Initial import of pipestatus-0.6.0, packaged for wip by Aleksey Cheusov.

Initial import of pipestatus-0.6.0, packaged for wip by Aleksey Cheusov.
Addresses PR 40250.

pipestatus - source file for POSIX shell that allows
to obtain an exit status of every program in a pipe.

                        MOTIVATION

When we program in shell we often run pipes like this

    prog1 args1 | prog2 args2 | ... | progN argsN

POSIX says that exit status of pipe is the exit status of LAST program
in it, i.e.  progN in our example. That is, exit status of all other
programs in pipe is silently ignored.  But in many situations exit
status of all programs in pipe should be checked to make program
robust. Some shells like BASH and ZSH have special extensions for
doing this but POSIX shell unfortunately doesn't provide an EASY way
for doing this.

In order to solve the problem, described above pipestatus was written.