bug#56636: 28.1.90; bibtex-beginning-of-entry does not always move point the the actual beginning

[Ihor Radchenko <yantar92@gmail.com>]

Hi,

Consider the following BibTeX entry:

@misc{placeholder,
  author =	 {Mamoru Miura <mamo0110@gmail.com>},
  created =	 {[2022-07-19 Tue 09:44]},
  howpublished = {ML:Org mode},
  link =
                  {notmuch:id:9F4AA657-D34B-4B85-A80D-1DD4B3017DB2@gmail.com},
  note =	 {Online; accessed 19 July 2022},
  title =	 {Re: Bug: Appointments duration and effort sums in
                  agenda column view [9.3.7 (release_9.3.7-700-ga1e5be
                  @ ~/.emacs.d/straight/build/org/)]},
  typealt =	 {email},
  year =	 2022,
}

Put the point at the "year" field and run
M-: (bibtex-beginning-of-entry)

Observed: Point moves to the @ ~/.emacs.d line.
Expected: Point moves to @misc

The problem is not only with the direct call to
bibtex-beginning-of-entry, but also shows up in functions that make use
of this function. For example, (bibtex-generate-autokey) or
(bibtex-autokey-get-title) will treat "title" field as empty in the
above scenario.

Best,
Ihor

In GNU Emacs 28.1.90 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.34, cairo version 1.16.0)
 of 2022-07-17 built on localhost
Repository revision: f5218385c064aa959650bfe49ca32795270851eb
Repository branch: emacs-28
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Gentoo Linux