Could it be a poorly sealed front windscreen?
Try pouring some water into the narrow groove/channel that you can see that runs along the top edge of the outside of the windscreen and see if any water makes it into the cabin.
I had a similar minor leak from front edge of headlining on two previous cars I owned, Rover and a new Honda. Some carefully placed silicone sealant applied to the windscreen rubber seal sorted out both cars. Having said that, the windscreen seal on the Jazz is a completely different design.
