Support plan

• which support plan is this issue covered by? (e.g. Community, Sponsor, or
  Enterprise): Community
• is this issue currently blocking your project? (yes/no): yes
• is this issue affecting a production system? (yes/no): no

Context

• node version: v10.17.0
• module (formidable) version: master #69b9a6e
• environment (e.g. node, browser, native, OS):
• used with (i.e. popular names of modules):
• any other relevant information:

What are you trying to achieve or the steps to reproduce?

In examples/store-files-on-s3.js, the filename received by uploadStream is still the part.filename since its the filename pass into this._newFile (

)
Not sure its designed by intention or not

What was the result you got?

origin filename

What result did you expect?

renamed filename if option.filename exists