_RSAPrivateKey' object has no attribute 'sign'

[peternye]

• I have checked that the SDK documentation doesn't solve my issue.
• I have checked that the API documentation doesn't solve my issue.
• I have searched the Box Developer Forums and my issue isn't already reported (or if it has been reported, I have attached a link to it, for reference).
• I have searched Issues in this repo and my issue isn't already reported.

Description of the Issue

Steps to Reproduce

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected Behavior

Error Message, Including Stack Trace

Screenshots

Versions Used

Python SDK:
Python:

[mwwoda]

Duplicate of #611.