Added in Linux's select issue to TODO.  Which may have to do with the
shell/sshd not sending a -TERM/-HUP to the grandchildren at the right
time in the exiting process.
diff --git a/TODO b/TODO
index cc274c8..c713580 100644
--- a/TODO
+++ b/TODO
@@ -11,6 +11,12 @@
 - Support 64bit ints on machines that lack 'long long' and u_intXX_t
   (tim@multitalents.net)
 
+- Linux hangs for 20 seconds when you do "sleep 20&exit".  All current
+  solutions break scp or leaves processes hanging around after the ssh
+  connection has ended.  It seems to be linked to two things.  One
+  select() under Linux is not as nice as others, and two the children
+  of the shell are not killed on exiting the shell.
+
 Documentation:
 - More and better
 
@@ -45,4 +51,3 @@
 
 - HP/UX: Provide DEPOT package scripts.
   (gilbert.r.loomis@saic.com)
-