SimpleJSON representation of pedigrees is incompatible between PhenoTips 1.3 and 1.4 when cancers are included

Steps to reproduce:

• In PhenoTips ver 1.4 create a pedigree, and add some cancers to a node

• export pedigree into SimpleJSON format

• Open a PhenoTips 1.3 instance and try to import the file; the import process fails; the progress bar never goes away

(the opposite also fails: create a pedigree in 1.3 and try to import it into 1.4)

Here is a sample SimpleJSON generated by 1.4 that can not be imported by 1.3.x. versions:

The same data in 1.3 SImpleJSON that can't be imported into 1.4: