Re: [PATCH] Unicode Lisp reader escapes

[Richard Stallman]

    All of these are incompatibilities on the Emacs Lisp side; except for the
    Unicode escapes, a C programmer can use any C escape desired in Emacs Lisp.

That being so, I think it is useful to keep that true, and implement
\u and \U in a way that is compatible with C.

We could install this now if someone writes changes for etc/NEWS and
the Lisp manual, as well as the code.