When I try to start the sage backend with Cantor, it gets stuck on the Initializing Session screen. I've put the stderr here: http://pastebin.com/DG5fRahm

Same here on 15.10, anybody knows whats going on?

The same on Manjaro.

As far as I can understand, it incorrectly recognizes sage's version and trying to use outdated version of it's API or anything else. So, why Cantor incorrectly recognizes sage's version and how can I force it to work with sage properly?

Output: http://pastebin.com/VzsavQkY
System: Up-to-date Manjaro, KDE, 4.4 kernel, etc.