Avoid failures in failure reporting

Signed-off-by: Philippe Ombredanne <pombredanne@nexb.com>

Author: pombredanne

tests/scancode/test_cli.py

@@ -318,11 +318,12 @@ def test_scan_works_with_no_processes_in_threaded_mode():
     # run the same scan with zero or one process
     result_file_0 = test_env.get_temp_file('json')
     args = ['--copyright', '--processes', '0', test_dir, '--json', result_file_0]
+    result0 = None
     try:
         result0 = run_scan_click(args)
     except Exception as e:
         print('Failed to run "test_scan_works_with_no_processes_in_threaded_mode" randomly. Ignoring failure: {e!r}')
-    assert 'Disabling multi-processing' in result0.output
+    assert result0 and 'Disabling multi-processing' in result0.output
 
     result_file_1 = test_env.get_temp_file('json')
     args = ['--copyright', '--processes', '1', test_dir, '--json', result_file_1]