Re: XML test error on Arch Linux

I wrote:
> I'll push this change in a little bit (still gotta write commit
> message) and indri should go back to green.  Unless one of the
> other animals complains, I'll set about back-patching in a
> day or two.

Well, that didn't take long: several animals are reporting
different error text for one or both of those new test cases.
It looks like I did indeed guess wrong about the output for
the libxml2 versions that match xml_2.out; but more
interestingly we have

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=widowbird&dt=2024-07-09%2019%3A30%3A07

@@ -287,7 +287,7 @@

 SELECT xmlparse(content '<unclosed>');
 ERROR:  invalid XML content
-DETAIL:  line 1: Premature end of data in tag unclosed line 1
+DETAIL:  line 1: chunk is not well balanced
 <unclosed>
           ^
 SELECT xmlparse(content '<parent><child></parent></child>');
@@ -358,7 +358,7 @@

 SELECT xmlparse(document '<unclosed>');
 ERROR:  invalid XML document
-DETAIL:  line 1: Premature end of data in tag unclosed line 1
+DETAIL:  line 1: EndTag: '</' not found
 <unclosed>
           ^
 SELECT xmlparse(document '<parent><child></parent></child>');

which proves that whatever version widowbird is running is
indeed capable of emitting XML_ERR_NOT_WELL_BALANCED with
no other error.  So my instinct to not suppress that
unconditionally was right.

At the moment I'm thinking that we should just remove those
new test cases again.  They are not valuable enough to
justify a new variant expected-file, while suppressing the
errdetail would remove whatever value they do have.

            regards, tom lane