Inconsistent handling of separators in List properties

To reproduce:

• Create a document D as a class
• Add a DBList property P with the following configuration
  • Display Type == INPUT
  • Multiple suggest
  • No relational storage
  • Multiselect separators (for editing) == ,
  • Join separator (for display) == ,
• Save it
• Create a page X with a object of type D
  • Edit P property and put a comma-separated list (for example "abc,def")
• Save the page X
• Reopen X in object mode and display the property P, it has been saved as "abc|def" (with a pipe instead of the comma)

Is | is hardcoded somewhere? Because it's a needed information in https://github.com/xwiki/xwiki-platform/pull/262/files#diff-c25f8254a5a3e4725650254773fb0e44R103