Rietveld should support warmup requests

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The codereview.appspot.com instance of Rietveld has the "always-on" feature 
(new in App Engine 1.4.0) turned on. Optionally, App Engine will also send 
"warm up" requests when it spins up a new instance.

See 
http://code.google.com/appengine/docs/python/config/appconfig.html#Inbound_Servi
ces .

We ought to enable this in app.yaml (according to the docs it won't hurt if 
always-on is not specified) and provide a handler for /_ah/warmup -- the 
handler should just return a 200 status immediately.

Original issue reported on code.google.com by guido@google.com on 6 Jan 2011 at 11:02

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Original comment by albrecht.andi on 6 Apr 2012 at 6:26

• Added labels: wa

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[Sorry, fat fingers problem, "wa" isn't a valid label :)]

Original comment by albrecht.andi on 6 Apr 2012 at 6:27

• Added labels: Easy, Component-Server
• Removed labels: wa

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Documentation was moved here: 
https://developers.google.com/appengine/docs/adminconsole/instances#Warmup_Reque
sts

Original comment by albrecht.andi on 6 Apr 2012 at 6:28