[development] avoiding duplicate issue followups

[Derek Wright]

yes, i know it's annoying that d.o keeps dying during issue followups  
(500s, squid errors, etc).  we're looking into it.  meanwhile, y'all  
should know:

YOUR FOLLOW-UP WAS POSTED THE FIRST TIME ...  ;)

you don't have to keep reloading and pressing "submit" over and over  
again.  that just produces duplicate follow-ups, and makes issues  
harder to read.  if you get an error, just navigate yourself back to  
the issue's page and you'll see your reply is there.

thanks,
-derek