playground: don't cache transient errors ("Error communicating with remote server.") #7730
Description
From the golang-nuts thread at https://groups.google.com/forum/#!topic/Golang-nuts/PJD1NAlm1Eg The play program at http://play.golang.org/p/JTAZnTb6am immediately shows "Error communicating with remote server." because whatever error occurred was cached. You can bust the cache by tweaking the program slightly (comments won't do -- try changing the Printf format string) and you'll see that sometimes the program will, in fact, give a response after some time (although it suffers from issue #7728). The playground shouldn't cache errors of this type; it can make perfectly good programs stop working. Two or three times in the past I've seen this occur with normal (much less pathological) programs as well, forcing the user to change a variable name or something in order to make it work again. (Unfortunately I don't have any of those other links available.)