Append unique with '*' character

I'm having trouble getting the append action to replace duplicate entries with the unique property in the following scenario:

// index.js template
/* PLOP_INJECT_EXPORT */
export * from './foo';

// plopfile.js action definition
ACTION: {
  type: 'append',
  data: {},
  path: indexFilePath,
  template: "export * from './foo';",
  pattern: '/* PLOP_INJECT_EXPORT */',
  unique: true,
}

// index.js file result
/* PLOP_INJECT_EXPORT */
export * from './foo';
export * from './foo';

Do you have any suggestions on how to get unique working in this situation?

This appears to be related to issue https://github.com/plopjs/plop/issues/174 which was closed.