bug#74409: 30.0.92; customize buffer for bibtex-biblatex-entry-alist also shows unformatted variable value

[Roland Winkler]

In emacs -Q load BibTeX mode and run

M-x customize-variable RET
bibtex-biblatex-entry-alist RET

The top of the customize buffer is clogged with the unformatted
variable value that hides the actual customization buffer.

I do not know whether this is related to bug #53606.  Like bug #53606,
the problem did not exist in earlier version of emacs (say, emacs 26.3).
But it started some time ago (confirmed with emacs 28.2).
Nothing changed on the side of BibTeX mode back then.


In GNU Emacs 30.0.92 (build 2, x86_64-pc-linux-gnu, GTK+ Version
 3.24.38, cairo version 1.16.0) of 2024-11-01 built on regnitz
Windowing system distributor 'The X.Org Foundation', version 11.0.12101007
System Description: Debian GNU/Linux 12 (bookworm)