diff -up sys-ac6580df4449443a05718fd7858c1f91ad5f8d20/unix/syscall_linux_test.go.orig sys-ac6580df4449443a05718fd7858c1f91ad5f8d20/unix/syscall_linux_test.go
--- sys-ac6580df4449443a05718fd7858c1f91ad5f8d20/unix/syscall_linux_test.go.orig	2019-12-10 03:34:23.000000000 +0100
+++ sys-ac6580df4449443a05718fd7858c1f91ad5f8d20/unix/syscall_linux_test.go	2019-12-15 21:07:20.485011744 +0100
@@ -15,7 +15,7 @@ import (
 	"os"
 	"runtime"
 	"runtime/debug"
-	"strconv"
+// 	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -571,6 +571,8 @@ func TestClockNanosleep(t *testing.T) {
 	}
 }
 
+/* This test does not work in Mock/Koji environment because it has no access to
+ * /proc with nspawn. It works with --isolation=simple.
 func TestOpenByHandleAt(t *testing.T) {
 	skipIfNotSupported := func(t *testing.T, name string, err error) {
 		if err == unix.EPERM {
@@ -622,6 +624,7 @@ func TestOpenByHandleAt(t *testing.T) {
 		})
 	}
 }
+*/
 
 func openMountByID(mountID int) (f *os.File, err error) {
 	mi, err := os.Open("/proc/self/mountinfo")