Regressions failures with libxml2 on ArchLinux

Hi all,

It's been one month since I have done some serious development with
Archlinux (I was abroad and away from the laptop dedicated to that),
and surprise, I can see failures in the PG regression tests, like the
following short extract (result compared to expected/xml.out):
SELECT xmlparse(document ' ');
ERROR: invalid XML document
! DETAIL: line 1: Start tag expected, '<' not found
----
SELECT xmlparse(document ' ');
ERROR: invalid XML document
! DETAIL: line 1: switching encoding : no input
!
! ^
! line 1: Start tag expected, '<' not found

Attached is the full diff of the thing.

On Archlinux the following package is being used, for something that
is rather up to date with upstream:
https://www.archlinux.org/packages/extra/x86_64/libxml2/
The last update of this package is dated of the 9th of July, which
corresponds more or less at the moment I have not been able to touch
my Linux laptop. So I would tend to think that something got broken
upstream because of this package update, and because the last thing
close enough to this code has been 0de791ed, but I have run the
regression tests on my Linux laptop as well.

I can notice as well that no buildfarm machines are running ArchLinux
now, so that's one reason why this got undetected until now. My own
machines running Archlinux ARM have been unplugged for a full month,
and I can see the failure there. They are not able to report back to
the buildfarm, but that's a separate issue, visibly that's an access
permission.

I have not investigated much this problem yet, but has somebody else
seen those diffs?

Thanks,
--
Michael