Pull up following revision(s) (requested by kre in ticket #337):
bin/sh/jobs.c: revision 1.91 (patch)

PR bin/52640  PR bin/52641

Don't delete jobs from the jobs table merely because they finished,
if they are not the job we are waiting upon.  (bin/52640 part 1)

In a sub-shell environment, don't allow wait to find jobs from the
parent shell that had already exited (before the sub-shell was
created) and return status for them as if they are our children.
(bin/52640 part 2)

Don't have the "jobs" command also be an implicit "wait" command
in non-interactive shells.  (bin/52641)

Use WCONTINUED (when it exists) so we can report on stopped jobs that
"mysteriously" move back to running state without the user issuing
a "bg" command (eg: kill -CONT <pid>)  Previously they would keep
being reported as stopped until they exited.
When a job is detected as having changed status just as we're
issuing a "jobs" command (i.e.: the change occurred between the last
prompt and the jobs command being entered) don't report it twice,
once from the status change, and then again in the jobs command
output.  Once is enough (keep the jobs output, suppress the other).

Apply some sanity to the way jobs_invalid is processed - ignore it
in getjob() instead of just ignoring it most of the time there, and
instead always check it before calling getjob() in situations where
we can handle only children of the current shell.  This allows the
(totally broken) save/clear/restore of jobs_invalid in jobscmd() to
be done away with (previously an error while in the clear state would
have left jobs_invalid incorrectly cleared - shouldn't have mattered
since jobs_invalid => subshell => error causes exit, but better to be safe).

Add/improve the DEBUG more tracing.

(martin)