Currently I have two versions of Emacs (system installed by apt-get: emacs26 and my own compiled version emacs27). They both us emacs.d
directory, and I wonder what happens the packages are incompatible with emacs27. May I use a different .emacs.d" such as
.emacs27.d` for only emacs27.
Is it okey to use the same directory for different version of Emacs.