Add a test for --keep-going option.

t/141-keep-going/all.do

@@ -0,0 +1,17 @@
+exec >&2
+. ../skip-if-minimal-do.sh
+
+rm -f out.log sort.log err.log
+redo --keep-going 1.ok 2.fail 3.fail 4.ok 5.ok 6.fail 7.ok >&err.log &&
+   exit 11  # expect it to return nonzero due to failures
+sort out.log >sort.log
+
+expect="1
+2 fail
+3 fail
+4
+5
+6 fail
+7"
+
+[ "$(cat sort.log)" = "$expect" ] || exit 22