So the OP is actually using Debian Stretch, and not Jessie, as he is bitten by the less-than-stellar decision by the Debian maintainers to enable "stable" network names. Unfortunately, the maintainers (both Debian as well as Raspbian) do not seem to realize that having stable, albeit unpredictable network interface names based on the MAC48 of the network adapter is a bad idea on server platforms, such as the Raspberry Pis.
The reason is that on the Raspberry Pi hardware platform, the builtin Ethernet and Wifi network interfaces are connected via USB. And Debian Stretch now enforces USB-based network interfaces to use the unpredictable naming scheme. This results in total confusion as can be seen here, as the unsuspecting users are completely left in the dark. How many users will understand what is going on?
Alas, to switch off this naming madness, follow these instructions from the Stretch release notes, to get back to stable and predictable network interface names on Raspbian, and I don't like this, how do I disable this? in particular. In short:
sudo ln -s /dev/null /etc/systemd/network/99-default.link
I fail to see how unpredictable network interface names fit into the self-esteem of Debian as being the stablest of stable.