internal/lsp/lsprpc: only propagate explicit GOWORK when using remote

When using gopls remote, existing go env vars are injected in the
initialize message. Setting GOWORK explicitly will impact cmd/go
invocations, for example "go list" during package load. The reason it
impacts is that gopls manually sets PWD to fix paths returned by cmd/go
if the working directory is inside a symlinked directory.

By only propagate GOWORK when it is explicitly set we will ensure that
the behavior is the same when running with or without remote.

See golang/go#51823.

Fixes golang/go#51825

Change-Id: I6280aa7d8208e5aee269f19356668c7713e9f0a4
Reviewed-on: https://go-review.googlesource.com/c/tools/+/394054
Trust: Pontus Leitzler <leitzler@gmail.com>
Run-TryBot: Pontus Leitzler <leitzler@gmail.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

internal/lsp/lsprpc/goenv.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"os"
 
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/gocommand"
@@ -54,7 +55,13 @@ func addGoEnvToInitializeRequestV2(ctx context.Context, req *jsonrpc2_v2.Request
 	if err != nil {
 		return err
 	}
+	// We don't want to propagate GOWORK unless explicitly set since that could mess with
+	// path inference during cmd/go invocations, see golang/go#51825.
+	_, goworkSet := os.LookupEnv("GOWORK")
 	for govar, value := range goenv {
+		if govar == "GOWORK" && !goworkSet {
+			continue
+		}
 		env[govar] = value
 	}
 	opts["env"] = env

internal/lsp/lsprpc/lsprpc.go

@@ -347,7 +347,13 @@ func addGoEnvToInitializeRequest(ctx context.Context, r jsonrpc2.Request) (jsonr
 	if err != nil {
 		return nil, err
 	}
+	// We don't want to propagate GOWORK unless explicitly set since that could mess with
+	// path inference during cmd/go invocations, see golang/go#51825.
+	_, goworkSet := os.LookupEnv("GOWORK")
 	for govar, value := range goenv {
+		if govar == "GOWORK" && !goworkSet {
+			continue
+		}
 		env[govar] = value
 	}
 	opts["env"] = env