internal/gomote: fix ExecuteCommand

This change fixes an incorrect variable in the ExecuteCommand endpoint.

For golang/go#47521
Updates golang/go#48742

Change-Id: Ic0f63e1ce83ba86a566981bdca16d57074dbb544
Reviewed-on: https://go-review.googlesource.com/c/build/+/411065
Run-TryBot: Carlos Amedee <carlos@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Auto-Submit: Carlos Amedee <carlos@golang.org>
diff --git a/internal/gomote/gomote.go b/internal/gomote/gomote.go
index 199f3ef..3f5f684 100644
--- a/internal/gomote/gomote.go
+++ b/internal/gomote/gomote.go
@@ -308,7 +308,7 @@
 		return status.Errorf(codes.Internal, "unable to retrieve configuration for instance")
 	}
 	remoteErr, execErr := bc.Exec(stream.Context(), req.GetCommand(), buildlet.ExecOpts{
-		Dir:         req.GetCommand(),
+		Dir:         req.GetDirectory(),
 		SystemLevel: req.GetSystemLevel(),
 		Output: &streamWriter{writeFunc: func(p []byte) (int, error) {
 			err := stream.Send(&protos.ExecuteCommandResponse{