compiling errors with latest TL update when upcasing some Greek literals.

[gmilde]

After an update of TL23 with tlshell, the following example says
! Missing = inserted for \ifnum. under pdflatex, xelatex, and lualatex.

\documentclass[a4paper]{article}

\ifdefined \UnicodeEncodingName
  \usepackage{fontspec}
  \setmainfont{FreeSerif}
\fi

\usepackage[greek,english,provide*=*]{babel}

\begin{document}

\foreignlanguage{greek}{ᾂ}

\foreignlanguage{greek}{\MakeUppercase{ᾂ}}

\end{document}

The log from pdflatex says:

This is pdfTeX, Version 3.141592653-2.6-1.40.25 (TeX Live 2023) (preloaded format=pdflatex 2023.6.21)  21 JUN 2023 13:41
entering extended mode
 restricted \write18 enabled.
 %&-line parsing enabled.
**chl
(./chl.tex
LaTeX2e <2023-06-01> patch level 1
L3 programming layer <2023-06-16>
(/usr/local/texlive/2023/texmf-dist/tex/latex/base/article.cls
Document Class: article 2023/05/17 v1.4n Standard LaTeX document class
(/usr/local/texlive/2023/texmf-dist/tex/latex/base/size10.clo
File: size10.clo 2023/05/17 v1.4n Standard LaTeX file (size option)
)
\c@part=\count185
\c@section=\count186
\c@subsection=\count187
\c@subsubsection=\count188
\c@paragraph=\count189
\c@subparagraph=\count190
\c@figure=\count191
\c@table=\count192
\abovecaptionskip=\skip48
\belowcaptionskip=\skip49
\bibindent=\dimen140
)
(/usr/local/texlive/2023/texmf-dist/tex/generic/babel/babel.sty
Package: babel 2023/05/11 v3.89 The Babel package
\babel@savecnt=\count193
\U@D=\dimen141
\l@unhyphenated=\language12

(/usr/local/texlive/2023/texmf-dist/tex/generic/babel/txtbabel.def)
\bbl@readstream=\read2
\bbl@dirlevel=\count194

(/usr/local/texlive/2023/texmf-dist/tex/generic/babel/locale/el/babel-greek.tex
)
Package babel Info: Importing data for greek
(babel)             from babel-el.ini. Reported on input line 4211.

(/usr/local/texlive/2023/texmf-dist/tex/generic/babel/locale/el/babel-greek.tex
)
(/usr/local/texlive/2023/texmf-dist/tex/generic/babel/locale/en/babel-english.t
ex)
Package babel Info: Importing data for english
(babel)             from babel-en.ini. Reported on input line 4238.
)
(/usr/local/texlive/2023/texmf-dist/tex/latex/l3backend/l3backend-pdftex.def
File: l3backend-pdftex.def 2023-04-19 L3 backend support: PDF output (pdfTeX)
\l__color_backend_stack_int=\count195
\l__pdf_internal_box=\box51
)
(./chl.aux)
\openout1 = `chl.aux'.

LaTeX Font Info:    Checking defaults for OML/cmm/m/it on input line 13.
LaTeX Font Info:    ... okay on input line 13.
LaTeX Font Info:    Checking defaults for OMS/cmsy/m/n on input line 13.
LaTeX Font Info:    ... okay on input line 13.
LaTeX Font Info:    Checking defaults for OT1/cmr/m/n on input line 13.
LaTeX Font Info:    ... okay on input line 13.
LaTeX Font Info:    Checking defaults for T1/cmr/m/n on input line 13.
LaTeX Font Info:    ... okay on input line 13.
LaTeX Font Info:    Checking defaults for TS1/cmr/m/n on input line 13.
LaTeX Font Info:    ... okay on input line 13.
LaTeX Font Info:    Checking defaults for OMX/cmex/m/n on input line 13.
LaTeX Font Info:    ... okay on input line 13.
LaTeX Font Info:    Checking defaults for U/cmr/m/n on input line 13.
LaTeX Font Info:    ... okay on input line 13.


! LaTeX Error: Unicode character ᾂ (U+1F82)
               not set up for use with LaTeX.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.15 \foreignlanguage{greek}{ᾂ}
                                 
? q
OK, entering \batchmode...
! Missing = inserted for \ifnum.
<to be read again> 
                   \begingroup 
l.17 \foreignlanguage{greek}{\MakeUppercase{ᾂ}}
                                                 
I was expecting to see `<', `=', or `>'. Didn't.

! Missing number, treated as zero.
<to be read again> 
                   \begingroup 
l.17 \foreignlanguage{greek}{\MakeUppercase{ᾂ}}
                                                 
A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)

! Missing = inserted for \ifnum.
<to be read again> 
                   \begingroup 
l.17 \foreignlanguage{greek}{\MakeUppercase{ᾂ}}
                                                 
I was expecting to see `<', `=', or `>'. Didn't.

! Missing number, treated as zero.
<to be read again> 
                   \begingroup 
l.17 \foreignlanguage{greek}{\MakeUppercase{ᾂ}}
                                                 
A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)


! LaTeX Error: Unicode character ᾼ (U+1FBC)
               not set up for use with LaTeX.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.17 \foreignlanguage{greek}{\MakeUppercase{ᾂ}}
                                                 
You may provide a definition with
\DeclareUnicodeCharacter 

 (./chl.aux)
 ***********
LaTeX2e <2023-06-01> patch level 1
L3 programming layer <2023-06-16>
 ***********
 ) 
Here is how much of TeX's memory you used:
 1763 strings out of 477557
 34755 string characters out of 5826600
 1851769 words of memory out of 5000000
 22355 multiletter control sequences out of 15000+600000
 513387 words of font info for 34 fonts, out of 8000000 for 9000
 59 hyphenation exceptions out of 8191
 41i,1n,50p,460b,522s stack positions out of 10000i,1000n,20000p,200000b,200000s

No pages of output.
PDF statistics:
 0 PDF objects out of 1000 (max. 8388607)
 0 named destinations out of 1000 (max. 500000)
 1 words of extra memory for PDF output out of 10000 (max. 10000000)

[josephwright]

OK, I see the issue - working on a fix