hush: fix stdin of backgrounded pipe 

function                                             old     new   delta
run_list                                            2450    2502     +52

diff --git a/shell/hush_test/hush-misc/redir5.tests b/shell/hush_test/hush-misc/redir5.tests
new file mode 100755
index 0000000..957f9c8
--- /dev/null
+++ b/shell/hush_test/hush-misc/redir5.tests
@@ -0,0 +1,13 @@
+echo "Backgrounded pipes shall have their stdin redirected to /dev/null"
+
+# 1. bash does not redirect stdin to /dev/null if it is interactive.
+# hush does it always (this is allowed by standards).
+
+# 2. Failure will result in this script hanging
+
+cat & wait; echo Zero:$?
+
+# This does not work for bash! bash bug?
+cat | cat & wait; echo Zero:$?
+
+echo Done