Save buffer resets major mode to Fundamental

[sphakka]

With Emacs-26.1 and latest edit-server (v1.14), any major mode set on the edit buffer is reset to Fundamental (or whatever defined via hooks, etc.) when saving the buffer.

[stsquad]

This is behaviour rather deep in Emacs' core file saving code.

[stsquad]

I should point out the easiest workaround is to ensure you name the file with the same extension as you which the major mode to be.