This patch fixes in intermittent failure in the regression tests:

there was a race condition between the "alter_table" and "rules"
regression tests. Depending on scheduling, sometimes an ALTER
TABLE command would operate on a relation created by the "rules"
tests, leading to unexpected results.

Neil Conway

src/test/regress/expected/alter_table.out

@@ -615,10 +615,10 @@ ERROR:  ALTER TABLE: relation "pg_class" is a system catalog
 alter table pg_class alter relname set not null;
 ERROR:  ALTER TABLE: relation "pg_class" is a system catalog
 -- try altering non-existent table, should fail
-alter table foo alter column bar set not null;
-ERROR:  Relation "foo" does not exist
-alter table foo alter column bar drop not null;
-ERROR:  Relation "foo" does not exist
+alter table non_existent alter column bar set not null;
+ERROR:  Relation "non_existent" does not exist
+alter table non_existent alter column bar drop not null;
+ERROR:  Relation "non_existent" does not exist
 -- test setting columns to null and not null and vice versa
 -- test checking for null values and primary key
 create table atacc1 (test int not null);

src/test/regress/sql/alter_table.sql

@@ -478,8 +478,8 @@ alter table pg_class alter column relname drop not null;
 alter table pg_class alter relname set not null;
 
 -- try altering non-existent table, should fail
-alter table foo alter column bar set not null;
-alter table foo alter column bar drop not null;
+alter table non_existent alter column bar set not null;
+alter table non_existent alter column bar drop not null;
 
 -- test setting columns to null and not null and vice versa
 -- test checking for null values and primary key