Fix that blind fix.

Author: arssher

testgres/pubsub.py

@@ -186,19 +186,17 @@ def catchup(self, username=None):
 Args:
 username: remote node's user name.
 """
-
 try:
-pub_lsn = pub.node.execute(query="select pg_current_wal_lsn()::text from pg_catalog.pg_stat_replication",
-dbname=None,
-username=None) # yapf: disable
+pub_lsn = self.pub.node.execute(query="select pg_current_wal_lsn()",
+dbname=None,
+username=None)[0][0] # yapf: disable
 # create dummy xact
-pub.node.execute(query="select txid_current()", dbname=None, username=None)
+self.pub.node.execute(query="select txid_current()", dbname=None, username=None)
 query = """
-select {} - replay_lsn <= 0
+select '{}'::pg_lsn - replay_lsn <= 0
 from pg_catalog.pg_stat_replication where application_name = '{}'
 """.format(pub_lsn, self.name)
 
-
 # wait until this LSN reaches subscriber
 self.pub.node.poll_query_until(
 query=query,