Running run_tests.sh with a vim executable (not neovim) produces garbled text output

[Yilin-Yang]

Running ./run_tests.sh from inside $PROJECT_ROOT/test produces output like:

Example Output, snipped at head and tail

                                                                              Starting Vader: /home/yiliny/plugins/vim-markbar/test/standalone-test-foldopen.vader
                                                            (1/8) [EXECUTE] Open Buffers
                                                                                            (2/8) [EXECUTE] Initialize, Declare Test Helpers
                                      (3/8) [EXECUTE] Set Up Folds and Marks
                                                                                (4/8) [     DO] jumping to a closed, level 1 fold opens that fold
                                           (4/8) [   THEN]
                                                              (5/8) [     DO] jumping to a closed, level 2 fold in closed level 1 fold opens that fold
                                                (5/8) [   THEN]
                                                                   (6/8) [     DO] jumping to a closed, level 2 fold above that fold in closed level 1 fold opens ONLY that fold
                                                                          (6/8) [   THEN]
                                                                                             (7/8) [     DO] jumping to a closed, level 3 fold in closed parent folds opens all three
                                                                               (7/8) [   THEN]
                                                                                                  (8/8) [     DO] jumping to any fold won't open it if 'foldopen' doesn't contain false
                                                                                 (8/8) [   THEN]
                                                                                                  Success/Total: 8/8
          Success/Total: 8/8 (assertions: 3/3)
                                              Elapsed time: 0.18 sec.