fix: map gid instead uid

fakeroot.go

@@ -27,6 +27,7 @@ func Command(name string, arg ...string) (*exec.Cmd, error) {
 // registered in the command.
 func Apply(cmd *exec.Cmd) error {
 	uid := os.Getuid()
+	gid := os.Getgid()
 
 	// If the user is already root, there's no need for fakeroot
 	if uid == 0 {
@@ -59,7 +60,7 @@ func Apply(cmd *exec.Cmd) error {
 
 	cmd.SysProcAttr.GidMappings = append(cmd.SysProcAttr.GidMappings, syscall.SysProcIDMap{
 		ContainerID: 0,
-		HostID:      uid,
+		HostID:      gid,
 		Size:        1,
 	})