bug: GODEBUG getting cached

[earthboundkid]

What version of Go are you using (go version)?

go version go1.16.6 darwin/amd64

Does this issue reproduce with the latest release?

It seems to reproduce with go1.17rc2.

What operating system and processor architecture are you using (go env)?

go env Output

GO111MODULE="on"
GOARCH="amd64"
GOBIN="/Users/adhoc/bin"
GOCACHE="/Users/adhoc/Library/Caches/go-build"
GOENV="/Users/adhoc/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/adhoc/src/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/adhoc/src/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.16.6/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.16.6/libexec/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.16.6"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/adhoc/src/exp/gotrace/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/p7/jc4qc9n94r3f6ylg0ssh1rq00000gs/T/go-build1481560794=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

main.go:

package main

import (
	"fmt"
	_ "google.golang.org/api/drive/v3"
)

func main() {
	fmt.Println("test program")
}

$ go mod init repro
$ go mod tidy
$ GODEBUG=inittrace=1 go run .
// snip init output
test program
$ GODEBUG=inittrace=1 go build .
// snip init output
$ go run .
// snip init output, again!
test program

In my quickie reproductions, it seems to be necessary to both go run and go build with GODEBUG set before doing it without to cause the issue. It also wasn't enough for the program to have no dependencies or the dependency to be rsc.io/quote. google.golang.org/api/drive/v3 was a real dependency in my program when I hit the bug. I don't know if it is necessary, but it is sufficient to trigger it. Maybe there needs to be some level of depth/size to the dependency to trigger it. Once the bug has been triggered, the debug information will stay even if you change fmt.Println("test program") to different text.

What did you expect to see?

No more init tracing when GODEBUG is unset.

What did you see instead?

Init continued to be traced until I ran go clean -cache.

[bcmills]

Duplicate of #44625