update vendor/

vendor/github.com/marcsauter/single/single_darwin.go

@@ -0,0 +1,15 @@
+package single
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+// Filename returns an absolute filename, appropriate for the operating system
+func (s *Single) Filename() string {
+	if len(Lockfile) > 0 {
+		return Lockfile
+	}
+	return filepath.Join(os.TempDir(), fmt.Sprintf("%s.lock", s.name))
+}