Cannot run Yaml validator multiple times

[hkorik]

Describe the bug
Using the blt validate:yaml:lint:files iteratively as part of a Robo watch task the task fails to find obvious violations after an initial violation is found. The behavior can be reproduced outside of a watch task by calling the validation task in a loop.

Same issue has been reported in version 10.x 3015 and patch has been merged into 10.x #3470 . Code changes appear to not have been implemented in v12.x for YamlCommand and only for the TwigCommand.

To Reproduce
Steps to reproduce the behavior, ideally starting from a fresh install of BLT:

1. Create the following files:

• docroot/themes/custom/test/one.yml:

one:
  - '

• docroot/themes/custom/test/two.yml:

two:
  - '

2. Create the following command function:

  /**
   * @command run:yaml:lint:files
   */
  public function testYamlLintFilesTask() {

    for ($i = 0; $i < 10; $i++) {

      try {
        $this->invokeBltCommand('validate:yaml:lint:files', ['file_list' => 'docroot/themes/custom/test/one.yml']);
      } catch (\Exception $exception) {
        // Do nothing.
      }

      try {
        $this->invokeBltCommand('validate:yaml:lint:files', ['file_list' => 'docroot/themes/custom/test/two.yml']);
      } catch (\Exception $exception) {
        // Do nothing.
      }

    }
  }

3. When I run:

$ blt run:yaml:lint:file

I get the following output:

$ blt run:yaml:lint:files
[warning] The xDebug extension is loaded. This will significantly decrease performance.
> validate:yaml:lint:files
Linting YAML files...
Iterating over fileset files.yaml...
''/var/www/meyers/vendor/bin/yaml-cli' lint '/var/www/meyers/docroot/themes/custom/nyunursing/one.yml'' exited with code 1 

[error]  Executing `'/var/www/meyers/vendor/bin/yaml-cli' lint '%s'` against fileset(s) files.yaml returned a non-zero exit code.`
For troubleshooting guidance and support, see https://docs.acquia.com/blt/support/ 
The command failed. This often indicates a problem with your configuration. Review the command output above for more detailed errors, and consider re-running with verbose output for more information.
Command `validate:yaml:lint:files 'docroot/themes/custom/nyunursing/one.yml'` exited with code 1.
For troubleshooting guidance and support, see https://docs.acquia.com/blt/support/
                                                    
 `validate:yaml:lint:files` finished with an error. 
                                                    
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
`validate:yaml:lint:files` finished successfully.

And I expected that violations would be found in one.yml and two.yml during each invocation.

With verbose output, BLT reports that the fileset is inexplicably empty:

$ blt run:yaml:lint:files -vvv

> validate:yaml:lint:files
Linting YAML files...
[debug] Gathering filesets from annotated methods...
[debug] Calling getFilesetPhpCustomModules on Acquia\Blt\Robo\Filesets\Filesets object...
[debug] Calling getFilesetPhpCustomThemes on Acquia\Blt\Robo\Filesets\Filesets object...
[debug] Calling getFilesetPhpTests on Acquia\Blt\Robo\Filesets\Filesets object...
[debug] Calling getFilesetFrontend on Acquia\Blt\Robo\Filesets\Filesets object...
[debug] Calling getFilesetTwig on Acquia\Blt\Robo\Filesets\Filesets object...
[debug] Calling getFilesetYaml on Acquia\Blt\Robo\Filesets\Filesets object...
[debug] Calling getFilesetFrontend on Acquia\Blt\Custom\Blt\Plugin\Filesets\Filesets object...
[debug] Calling getFilesetYaml on Acquia\Blt\Custom\Blt\Plugin\Filesets\Filesets object...
[debug] Calling getFilesetPhpCustomModules on Acquia\Blt\Custom\Blt\Plugin\Filesets\Filesets object...
[debug] Calling getFilesetPhpCustomThemes on Acquia\Blt\Custom\Blt\Plugin\Filesets\Filesets object...
[debug] Calling getFilesetPhpTests on Acquia\Blt\Custom\Blt\Plugin\Filesets\Filesets object...
[debug] Calling getFilesetTwig on Acquia\Blt\Custom\Blt\Plugin\Filesets\Filesets object...
Iterating over fileset files.yaml...
[ParallelExec] '/var/www/meyers/vendor/bin/yaml-cli' lint '/var/www/meyers/docroot/themes/custom/nyunursing/one.yml'
[ParallelExec]  ''/var/www/meyers/vendor/bin/yaml-cli' lint '/var/www/meyers/docroot/themes/custom/nyunursing/one.yml'' exited with code 1 
  Time 0.101s
[ParallelExec]  Exit code 1  Time 0.101s
''/var/www/meyers/vendor/bin/yaml-cli' lint '/var/www/meyers/docroot/themes/custom/nyunursing/one.yml'' exited with code 1 

[error]  Executing `'/var/www/meyers/vendor/bin/yaml-cli' lint '%s'` against fileset(s) files.yaml returned a non-zero exit code.`
For troubleshooting guidance and support, see https://docs.acquia.com/blt/support/ 
The command failed. This often indicates a problem with your configuration. Review the command output above for more detailed errors, and consider re-running with verbose output for more information.
Command `validate:yaml:lint:files 'docroot/themes/custom/nyunursing/one.yml'` exited with code 1.
For troubleshooting guidance and support, see https://docs.acquia.com/blt/support/
                                                    
 `validate:yaml:lint:files` finished with an error. 
                                                    
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
> validate:yaml:lint:files
Linting YAML files...
[info] No files were found in fileset files.yaml. Skipped.
`validate:yaml:lint:files` finished successfully.
9.433s total time elapsed.