Re: Use \if/\endif to remove non-libxml2 expected output in regression tests

I wrote:
> It's kind of sad that this issue is still present in the wild ten
> years later.  But anyway, I wonder if we could dodge the issue
> simply by modifying these error-provoking cases to have some
> whitespace at the end of the XML input?  I don't think I have
> a problematic version of libxml2 to test that with, though.

Hah, this idea does mostly work.  Finding that no system I had at
hand had a libxml2 old enough to exhibit the problem, I installed
libxml2 2.9.3 from source.  (That's the first version containing
the problematic CVE fix, and it does behave as xml_2.out expects.)
I found that four of the inconsistent messages could be fixed this
way.  The other three problem cases have input like 'one');
 INSERT INTO xmltest VALUES (2, 'two');
-INSERT INTO xmltest VALUES (3, 'two  ');
 ERROR:  invalid XML content
-LINE 1: INSERT INTO xmltest VALUES (3, 'two  ');
                                        ^
-DETAIL:  line 1: Couldn't find end of Start Tag wrong line 1
-two  
+                  ^
 SELECT * FROM xmltest;
  id |        data        
 ----+--------------------
@@ -89,13 +89,13 @@ SELECT xmlconcat(1, 2);
 ERROR:  argument of XMLCONCAT must be type xml, not type integer
 LINE 1: SELECT xmlconcat(1, 2);
                          ^
-SELECT xmlconcat('bad', '  ');
 ERROR:  invalid XML content
-LINE 1: SELECT xmlconcat('bad', '  ');
                                 ^
-DETAIL:  line 1: Couldn't find end of Start Tag syntax line 1
-  
+                ^
 SELECT xmlconcat('', NULL, '');
   xmlconcat   
 --------------
@@ -271,13 +271,13 @@ SELECT xmlparse(content '');
  
 (1 row)
 
-SELECT xmlparse(content '&idontexist;');
+SELECT xmlparse(content '&idontexist;  ');
 ERROR:  invalid XML content
 DETAIL:  line 1: Entity 'idontexist' not defined
-&idontexist;
+&idontexist;  
                        ^
 line 1: Opening and ending tag mismatch: twoerrors line 1 and unbalanced
-&idontexist;
+&idontexist;  
                                     ^
 SELECT xmlparse(content '');
       xmlparse       
@@ -285,11 +285,11 @@ SELECT xmlparse(content '');
  
 (1 row)
 
-SELECT xmlparse(document '   ');
+SELECT xmlparse(document '!');
 ERROR:  invalid XML document
 DETAIL:  line 1: Start tag expected, '<' not found
-   
-   ^
+!
+^
 SELECT xmlparse(document 'abc');
 ERROR:  invalid XML document
 DETAIL:  line 1: Start tag expected, '<' not found
@@ -301,21 +301,21 @@ SELECT xmlparse(document 'x');
  x
 (1 row)
 
-SELECT xmlparse(document '&');
+SELECT xmlparse(document '&  ');
 ERROR:  invalid XML document
 DETAIL:  line 1: xmlParseEntityRef: no name
-&
+&  
                 ^
 line 1: Opening and ending tag mismatch: invalidentity line 1 and abc
-&
+&  
                       ^
-SELECT xmlparse(document '&idontexist;');
+SELECT xmlparse(document '&idontexist;  ');
 ERROR:  invalid XML document
 DETAIL:  line 1: Entity 'idontexist' not defined
-&idontexist;
+&idontexist;  
                              ^
 line 1: Opening and ending tag mismatch: undefinedentity line 1 and abc
-&idontexist;
+&idontexist;  
                                    ^
 SELECT xmlparse(document '');
          xmlparse          
@@ -329,13 +329,13 @@ SELECT xmlparse(document '');
  
 (1 row)
 
-SELECT xmlparse(document '&idontexist;');
+SELECT xmlparse(document '&idontexist;  ');
 ERROR:  invalid XML document
 DETAIL:  line 1: Entity 'idontexist' not defined
-&idontexist;
+&idontexist;  
                        ^
 line 1: Opening and ending tag mismatch: twoerrors line 1 and unbalanced
-&idontexist;
+&idontexist;  
                                     ^
 SELECT xmlparse(document '');
       xmlparse       
diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql
index 2b8445e499e..0366b776119 100644
--- a/src/test/regress/sql/xml.sql
+++ b/src/test/regress/sql/xml.sql
@@ -5,7 +5,7 @@ CREATE TABLE xmltest (
 
 INSERT INTO xmltest VALUES (1, 'one');
 INSERT INTO xmltest VALUES (2, 'two');
-INSERT INTO xmltest VALUES (3, 'two  ');
 
 SELECT * FROM xmltest;
 
@@ -30,7 +30,7 @@ SELECT xmlconcat(xmlcomment('hello'),
 
 SELECT xmlconcat('hello', 'you');
 SELECT xmlconcat(1, 2);
-SELECT xmlconcat('bad', '  ');
 SELECT xmlconcat('', NULL, '');
 SELECT xmlconcat('', NULL, '');
 SELECT xmlconcat(NULL);
@@ -75,17 +75,17 @@ SELECT xmlparse(content '&');
 SELECT xmlparse(content '&idontexist;');
 SELECT xmlparse(content '');
 SELECT xmlparse(content '');
-SELECT xmlparse(content '&idontexist;');
+SELECT xmlparse(content '&idontexist;  ');
 SELECT xmlparse(content '');
 
-SELECT xmlparse(document '   ');
+SELECT xmlparse(document '!');
 SELECT xmlparse(document 'abc');
 SELECT xmlparse(document 'x');
-SELECT xmlparse(document '&');
-SELECT xmlparse(document '&idontexist;');
+SELECT xmlparse(document '&  ');
+SELECT xmlparse(document '&idontexist;  ');
 SELECT xmlparse(document '');
 SELECT xmlparse(document '');
-SELECT xmlparse(document '&idontexist;');
+SELECT xmlparse(document '&idontexist;  ');
 SELECT xmlparse(document '');