appengine.NewContext panics on flex

[broady]

via GoogleCloudPlatform/golang-samples#264

Probably caused by #68?

/cc @zombiezen

[zombiezen]

Took a look and that panic is a different one. #68 makes it panic if an App Engine API is called on a context derived from context.Background. The panic you are seeing is what happens if you attempt to obtain a Context for an http.Request that didn't originate from App Engine. Is there some middleware that is altering the request that the handler receives?

[broady]

yes, via appengine.Main(). An hour ago, I thought this was a regression, but after thinking more, it's always been like this.

[zombiezen]

Right. appengine.NewContext doesn't work in the slightest on Flex; it only worked on Managed VMs. This is working as intended, but does seem to have a high foot-gun factor.