How to stop 'apt update' + 'apt upgrade' from updating one particular library?

[Chris Green]

On Tue, Nov 23, 2021 at 02:56:58PM +0800, Lily White wrote:
> On 2021/11/18 23:22, Chris Green wrote:
> > There is a bug in the version 10.37 of libpcre2-8-0:amd64 which installs
> > with [x]ubuntu 21.10.  The bug is not present in the previous version.
> > 
> > Is there any way to prevent apt from updating that particular library
> > to the latest version when I do an overall 'apt update' and 'apt
> > upgrade'?
> > 
> > Fortunately, at present, I have nothing which depends on the newest
> > version of libpcre2-8-0:amd64 so everything works fine with the
> > previous version.  Hopefully the bug will get fixed and I will be able
> > to allow a newer version to be installed but for the present I want to
> > lock my installed version of libpcre2-8-0:amd64 at 10.36.
> > 

> Though you've solved it I'd still like to ask whether it is indeed a
> regression in the package itself. If it is, did you report it to the
> maintainers' bug tracker?
> 
It's a known bug that's in both 10.37 and 10.38, the effect is that
regular expressions that should match simply don't match - rather
fundamantal.

It bit me in Dokuwiki, the main symptom was that links which in
Dokuwiki are [[this is a link|text]] were simply ignored and came out
on the page as text complete with [[ and ]].  It's rather a
fundamental flaw in a string matching library!  It's very inconsistent
though, most links work OK, just some are missed and re-arranging text
and/or restarting might fix things.

It can be helped (as in less frequent problems) by disabling JIT in PHP.

It's supposedly fixed in 10.39.

-- 
Chris Green