vendor: Update github.com/calmh/du (ref #4079)

vendor/github.com/calmh/du/diskusage_windows_test.go

@@ -0,0 +1,27 @@
+package du
+
+import "testing"
+
+func TestDiskUsage(t *testing.T) {
+	cases := []struct {
+		path string
+		ok   bool
+	}{
+		{"c:\\", true},
+		{"c:\\windows", true},
+		{"c:\\aux", false},
+		{"c:\\does-not-exist-09sadkjhdsa98234bj23hgasd98", false},
+	}
+	for _, tc := range cases {
+		res, err := Get(tc.path)
+		if tc.ok {
+			if err != nil {
+				t.Errorf("Unexpected error Get(%q) => %v", tc.path, err)
+			} else if res.TotalBytes == 0 || res.AvailBytes == 0 || res.FreeBytes == 0 {
+				t.Errorf("Suspicious result Get(%q) => %v", tc.path, res)
+			}
+		} else if err == nil {
+			t.Errorf("Unexpected nil error in Get(%q)", tc.path)
+		}
+	}
+}