bug#4717: 23.1.50; C-M-h in bibtex mode

[Leo]

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

C-M-h which runs bibtex-mark-entry in BibTeX-mode seems to be
inconsistent with C-M-h in other modes. For example, C-M-h in
emacs-lisp-mode will mark the 'defun' with highlighted region and the
point in the beginning of the region.

In BibTeX mode, however, the region is _not_ highlighted and the point
is left at the end of the region.

I wonder if this inconsistency can be done away with.

Best wishes,

Leo