Bug: `eval_capture` has a race condition that can cause CI to fail

[balupton]

Will use this issue to track progress on this ongoing issue.

/cc @molleweide

resources:

• https://gist.github.com/balupton/21ded5cefc26dc20833e6ed606209e1b
• c1fe25b
• 9b4177f
• 596a6bd#diff-fdce5cb2b4ffb7374573ddbe18177d5d871da104db96cce483934d4a0dc50ea6
• 9400e2f
• Bug: ci macos test failures are not reported #203 (comment)
• c1fe25b#diff-fdce5cb2b4ffb7374573ddbe18177d5d871da104db96cce483934d4a0dc50ea6R221
• https://github.com/bevry/dorothy/blob/c1fe25b4a2382fc979dace2d23ee15efd60d8c28/commands/eval-capture
• https://github.com/bevry/dorothy/blob/master/docs/bash/versions.md
• https://git.savannah.gnu.org/cgit/bash.git/tree/CHANGES

[balupton]

proof-of-concept solution:

echo-style --stdout='my-stdout' --stderr='my-stderr' \
	<(tee stdout.txt; touch stdout.complete) \
	2> <(tee stderr.txt >/dev/stderr; touch stderr.complete)
while [[ ! -f stdout.complete || ! -f stderr.complete ]]; do
	sleep 0.1
done
cat stdout.txt
cat stderr.txt 2>/dev/stderr
rm stdout.txt stderr.txt stdout.complete stderr.complete