Problem: Some old comments suggest looking "above" for code definitions.
But that is out of date.

Remove the "above" text and update comment.

Problem: In _process_setresult() if the plug name is not found
in the inputted arglist, it can result in a segfault.  This
can occur when power operations on dependent targets (e.g. the
parent of node needs to be powered on) have errors, leading to
an unexpected host having a "power result".

Check that arg is non-NULL before trying to dereference it.

Fixes chaos#197

Problem: If an error occurs on a parent, the error should not
be output.  It should only be output on the descendants that
depend on the parent.

Check the output_result flag before outputting error messages.

Problem: There are no tests for the special case where a parent
results in a error and leads to a dependency error with
the setresult statement.

Add coverage via t0037-cray-ex.t.