fix #383 – ensure files are not matched twice

[martinkutter]

[…dharthkp/bundlesize/issues/383)

Description

Motivation and Context

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• If my change requires a change to the documentation I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I created an issue for the Pull Request
  ](Allow default file size to ensure no big files are added later siddharthkp/bundlesize#383)

[helgenlechner]

@martinkutter Habe nichts auszusetzen außer ein paar Englischverbesserungen :)