A signed recovery.img (with TWRP inside) for the Fairphone 2, to be used with
"fastboot boot <image>".

The signature is just proforma, it's not checked by the phone.

Original images from: https://dl.twrp.me/FP2/

Simply reboot after use, your phone will be as before. No root or other
modifications needed, just use the above command inside the fastboot-mode
(press VOL- on start).