fs: fix parsing of times and durations of the form "YYYY-MM-DD HH:MM:SS"

Before this fix, the parsing code gave an error like this

    parsing "2022-08-02 07:00:00" as fs.Time failed: expected newline

This was due to the Scan call failing to read all the data.

This patch fixes that, and redoes the tests

fs/parseduration_test.go

@@ -145,11 +145,28 @@ func TestDurationReadableString(t *testing.T) {
 }
 
 func TestDurationScan(t *testing.T) {
-	var v Duration
-	n, err := fmt.Sscan(" 17m ", &v)
-	require.NoError(t, err)
-	assert.Equal(t, 1, n)
-	assert.Equal(t, Duration(17*60*time.Second), v)
+	now := time.Date(2020, 9, 5, 8, 15, 5, 250, time.UTC)
+	oldTimeNowFunc := timeNowFunc
+	timeNowFunc = func() time.Time { return now }
+	defer func() { timeNowFunc = oldTimeNowFunc }()
+
+	for _, test := range []struct {
+		in   string
+		want Duration
+	}{
+		{"17m", Duration(17 * time.Minute)},
+		{"-12h", Duration(-12 * time.Hour)},
+		{"0", Duration(0)},
+		{"off", DurationOff},
+		{"2022-03-26T17:48:19Z", Duration(now.Sub(time.Date(2022, 03, 26, 17, 48, 19, 0, time.UTC)))},
+		{"2022-03-26 17:48:19", Duration(now.Sub(time.Date(2022, 03, 26, 17, 48, 19, 0, time.Local)))},
+	} {
+		var got Duration
+		n, err := fmt.Sscan(test.in, &got)
+		require.NoError(t, err)
+		assert.Equal(t, 1, n)
+		assert.Equal(t, test.want, got)
+	}
 }
 
 func TestParseUnmarshalJSON(t *testing.T) {