Fails when tests run in parallel or maxInstances more than 1.

[bdarwin]

If i do this i suppose multiple specs trying to create the directory and one of it fails as other spec might have created the directory already.

exports.config = {
    capabilities: {
        'browserName': 'phantomjs',
        'maxInstances': 5,
   }
}

Error: Could not create directory <path>. 

This happens frequently but not all the time though.

If I change the maxInstances to 1 it works fine, but this makes my build slower.
I tried providing a random path using pathBuilder, but then I am facing issues to merge the results into single report.

Any clues?