Steps to reproduce problem:
1. Create doc of type File with "Skip version increment"
2. Invoke CMIS cancelCheckOut Browser Binding operation on doc using curl
Current Result: doc is deleted
Improved Result: special error is returned indicating that a CMIS cancelCheckOut operation cannot be performed against a non-versioned document (which has no cmis:versionLabel)
Using the configuration property org.nuxeo.cmis.errorOnCancelCheckOutOfDraftVersion it's now possible to enable the returning of a versioning error when an attempt is made to call cancelCheckOut on a draft (live document with no version):