Ah that explains it. That SD card build pointed to that repository because at the time the version in the main Raspbian repositories were not up to date enough. Now the opposite is true 
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TBH as you are on a Jessie based SD, the path of least resistance will be to get a new SD Card, either from the shop (preloaded) or download a new image and flash it to the SD card. Warning, if you have a Pi2 you need to follow the instructions on the download page. Having looked they are a bit hidden so…
To use this image on Pi2 remove the following lines from /boot/config.txt :
arm_freq=1200
arm_freq_min=600
Also note Node-Red and OpenHAB have been removed from this image as standard (you can install them if you wish).
Run a backup from your current system. Put the new card in, leave it for a while to update itself, then upload the backup to the new card.
You should be back in business.
@TrystanLea - could these update instructions be converted to a Wiki page as repeating them is getting a little tiresome? Perhaps even add a link to them from the Admin Page if the image is old enough.