Cause: could not enable GOA configured account Mail part again
Consequence: a GOA account had been configured, evolution-data-server picked its enabled parts and offered them to clients. Once the Mail part was disabled, it's re-enable didn't provide the Mail part to the clients again, due to deleted underlying .source files.
Fix: File system change notifications are processed properly now, no delete is done (file modification generated delete & create events)
Result: Mail part (or even other parts) can be disabled and enabled multiple times without losing them.