Hello,
The test server at
http://cosmos.mat.uam.es:8888/ is currently running Sage-8.0 without any modifications. I would very much like to switch to it for the main public servers as well for this and future releases. The only difference is in something related to handling "magic" % commands (see
https://github.com/sagemath/sage/compare/8.0...novoselt:sagecell for the difference). In my view current handling of % directives in SageMathCell is broken and inconsistent anyway, so it would be better to at least not break it in a special way requiring a separate fork. Besides, there is a way to specify several input languages without %. If you use % in cells, please see if there are any differences for you!
Thank you,
Andrey