PANGE LINGUA

Ian Robins observed to me today that the New English Hymnal has a mistake in the Latin at the headings of both the Pange Lingua hymns.

That is

Hymn 78 (Sing my tongue the glorious battle) is headed pangue lingua gloriosi proelium certaminis


and

hymn 268 (Of the glorious body telling) is headed pangue lingua gloriosi corporis mysterium.

Since when was the verb pangere (to compose or write verses) written with a u? Or since when was its second person imperative form written with a u? I am not aware of any verb that has such a form.

The title of the tune is correctly written PANGE LINGUA in both cases.

Does any detective have a way of discovering how this new corruption arrived in the NEH?