tests: fix for backup.BackupTest.test_backup_detect_corruption

tests/backup.py

@@ -469,12 +469,16 @@ class BackupTest(ProbackupTest, unittest.TestCase):
             "postgres",
             "select pg_relation_filepath('t_heap')").rstrip()
 
+        node.stop()
+
         with open(os.path.join(node.data_dir, heap_path), "rb+", 0) as f:
                 f.seek(9000)
                 f.write(b"bla")
                 f.flush()
                 f.close
 
+        node.slow_start()
+
         try:
             self.backup_node(
                 backup_dir, 'node', node,
@@ -486,6 +490,16 @@ class BackupTest(ProbackupTest, unittest.TestCase):
                 "\n Output: {0} \n CMD: {1}".format(
                     repr(self.output), self.cmd))
         except ProbackupException as e:
+            if self.ptrack:
+                self.assertTrue(
+                    'WARNING:  page verification failed, '
+                    'calculated checksum' in e.message and
+                    'ERROR: query failed: ERROR:  '
+                    'invalid page in block 1 of relation' in e.message and
+                    'ERROR: Data files transferring failed' in e.message,
+                    '\n Unexpected Error Message: {0}\n CMD: {1}'.format(
+                        repr(e.message), self.cmd))
+            else:
                 if self.remote:
                     self.assertTrue(
                         "ERROR: Failed to read file" in e.message and