This implements a pipestatus command, as discussed in bug 566342 [1]
and on IRC.

Subject to approval by the council, the command would be added in
EAPI 9. Its definition in the Package Manager Specification would be
along the lines of:

╓────
║ Tests the shell's pipe status array, i.e. the exit status of the
║ command(s) in the most recently executed foreground pipeline.
║ Returns shell true (0) if all elements are zero, or the last
║ non-zero element otherwise. If called with -v as the first argument,
║ also outputs the pipe status array as a space-separated list.
╙────

The "assert" command could then be banned (either in the same EAPI or
in the following EAPI), typically to be replaced by "pipestatus || die".

I would commit the eclass after the next council meeting, and obviously
only under the condition that the council will pre-approve the command
for EAPI 9.

[1] https://bugs.gentoo.org/566342