cmd/go: 'go get' failed in go1.13beta1 if proxy serves non-404/410 response code

[oiooj]

context

https://goproxy.io/github.com/@latest returns code 500, not 404, but this design found a bug in go1.13beta1.

description

if we run go get -v golang.org/x/tools/cmd/gopls

use go1.12:

Sosara@MBA:/tmp$ go get -v golang.org/x/tools/cmd/gopls
go: finding golang.org/x/tools/cmd/gopls latest
go: finding golang.org/x latest
go: finding golang.org latest
go: finding golang.org/x/tools/cmd latest
go: finding golang.org/x/tools latest
go: downloading golang.org/x/tools v0.0.0-20190606050223-4d9ae51c2468
go: extracting golang.org/x/tools v0.0.0-20190606050223-4d9ae51c2468
go: downloading golang.org/x/sync v0.0.0-20190423024810-112230192c58
go: extracting golang.org/x/sync v0.0.0-20190423024810-112230192c58
go: finding golang.org/x/sync v0.0.0-20190423024810-112230192c58

but use go1.13beta1

# go version
go version go1.13beta1 linux/amd64

# go get -v golang.org/x/tools/cmd/gopls
go: finding golang.org/x/text/language latest
go: finding golang.org latest
go: finding golang.org/x/text v0.3.2
go: finding golang.org/x latest
go: downloading golang.org/x/text v0.3.2
go: extracting golang.org/x/text v0.3.2
go get golang.org/x/text/language: module golang.org: reading https://goproxy.io/golang.org/@latest: 500 Internal Server Error

We already found the prefix, but the error also returned.
Introduced by https://go-review.googlesource.com/c/go/+/177958

[gopherbot]

Change https://golang.org/cl/185478 mentions this issue: cmd/go/internal/modload: ignore error if we found the prefix in queryPrefixModules

[bcmills]

Why is the proxy returning status 500 for this path? That seems like the bug to fix.

(See previously #31913.)

[oiooj]

Why is the proxy returning status 500 for this path? That seems like the bug to fix.

@bcmills Thanks, The goproxy.io built before CL173441, and it breaks user's go get in go1.13beata1, I will fix the proxy server.