v3: Fix trailing slash in routing removed

[ikawaha]

The routing trailing slash problem fixed in v1 seems to be occurring again in v3.
This patch fixes it in the same way as v1.

see also. #1283

[raphael]

Great, thank you! Can you please also back-port to v2, thanks!

[trestletech]

Is the handling here different for POST requests? I'm seeing

My design is:

		HTTP(func() {
			POST("/blah/")
			Response(StatusOK)
		})

but I'm seeing:

[srvrapi] 21:50:27 id=oEcoo0o3 req=POST /blah/ from=172.17.0.1
[srvrapi] 21:50:27 id=oEcoo0o3 status=301 bytes=0 time=143.6µs
[srvrapi] 21:50:27 id=SUOWXrMt req=GET /blah from=172.17.0.1
[srvrapi] 21:50:27 id=SUOWXrMt status=405 bytes=0 time=68.5µs

(where the 405 indicates that the GET call to that path is invalid). I tried updating to the latest commit using go get -u goa.design/goa/v3@4064ab219b39e4741ec61a06f62b6ba5906ffae0 but still see this behavior.

[trestletech]

Just confirmed that if I add the trailing slash back into mux.Handle("POST", "/learnr", f) in the generated server.go, it starts working for me.

Did I fail to update to the right version, or is this bug still open for POST requests?

[trestletech]

Oops. I think I was forgetting to rerun generate. Once I did that, I think we're back online. Thanks for the fix and sorry for the false alarm!