resilient/runner_exporter: look for modified backup files in the original folders

and not in the backuped files.
If we look in the backup files, then of course we find modified files, which are
the ones that have just been copied from the instance folders

slapos/resilient/runner_exporter.py

@@ -146,7 +146,7 @@ def runExport():
   time.sleep(10)
 
   # Check that export didn't happen during backup of instances
-  with CwdContextManager(backup_runner_path):
+  with CwdContextManager(os.path.join(runner_working_path, 'instance')):
     if backupFilesWereModifiedDuringExport(export_start_date):
       print("ERROR: Some backups are not consistent, exporter should be re-run."
             " Let's sleep %s minutes, to let the backup end..." % args.backup_wait_time)