Fix comments.

bash.sh

@@ -1,6 +1,7 @@
 #!/bin/bash
+set -e
 
 kill_child_jobs() {
-    # From https://stackoverflow.com/a/360275
+    # From https://unix.stackexchange.com/a/544167
     while kill %% 2>/dev/null; do sleep 0; done
 }

dash.sh

@@ -1,7 +1,6 @@
 #!/bin/sh
 set -e
 
-# From https://stackoverflow.com/a/360275
 kill_child_jobs() {
     echo "In kill_child_jobs()..."
     # Workaround for https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=482999

zsh.sh

@@ -1,7 +1,6 @@
 #!/bin/zsh
 set -e
 
-# From https://stackoverflow.com/a/360275
 kill_child_jobs() {
     echo "In kill_child_jobs()..."