[Chapel Merge] Fix problems with mandelbrot tests in gasnet confi

Branch: refs/heads/master
Revision: 41cc7d7
Author: mppf
Log Message:

Merge pull request #16610 from mppf/mandelbrot-slurm

Fix problems with mandelbrot tests in gasnet configs

Some GASNet configs can produce extra error output
at the end of the test. Adjust the mandelbrot.prediff
to show that (to make it easier to see the problem in
case it comes up again) and updated sub_test to
use surrogate-escape encoding when checking for known
failure patterns.

  • [x] mandelbrot test passes on a Cray CS system
  • [x] full local testing

Reviewed by @lydia-duncan - thanks!

Modified Files:
M test/release/examples/benchmarks/shootout/mandelbrot.prediff
M util/test/sub_test

Compare: https://github.com/chapel-lang/chapel/compare/db5091a0366b...41cc7d7897f5