Add a simple test for SIGINT out of loops

tests/checks/sigint.fish

@@ -0,0 +1,11 @@
+#RUN: %fish -C "set helper %fish_test_helper" %s
+
+# Ensure we can break from a while loop.
+
+echo About to sigint
+$helper sigint_parent &
+while true ; end
+echo I should not be printed because I got sigint
+
+#CHECK: About to sigint
+#CHECKERR: Sent SIGINT to {{\d*}}

tests/test.fish

@@ -75,7 +75,10 @@ function test_littlecheck_file
     set -l file $argv[1]
     echo -n "Testing file $file ... "
     set starttime (timestamp)
-    $python ../littlecheck.py -s fish=../test/root/bin/fish $file
+    $python ../littlecheck.py \
+      -s fish=../test/root/bin/fish \
+      -s fish_test_helper=../test/root/bin/fish_test_helper \
+      $file
     set -l exit_status $status
     set -l res ok
     set test_duration (delta $starttime)