Use errors.Wrap to preserve original error

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libnetwork/netutils/utils_linux.go

@@ -13,6 +13,7 @@ import (
 	"github.com/docker/libnetwork/osl"
 	"github.com/docker/libnetwork/resolvconf"
 	"github.com/docker/libnetwork/types"
+	"github.com/pkg/errors"
 	"github.com/vishvananda/netlink"
 )
 
@@ -97,8 +98,7 @@ func ElectInterfaceAddresses(name string) ([]*net.IPNet, []*net.IPNet, error) {
 		// Choose from predefined local scope networks
 		v4Net, err := FindAvailableNetwork(ipamutils.PredefinedLocalScopeDefaultNetworks)
 		if err != nil {
-			return nil, nil, fmt.Errorf("%s, PredefinedLocalScopeDefaultNetworks List: %+v",
-				err.Error(),
+			return nil, nil, errors.Wrapf(err, "PredefinedLocalScopeDefaultNetworks List: %+v",
 				ipamutils.PredefinedLocalScopeDefaultNetworks)
 		}
 		v4Nets = append(v4Nets, v4Net)