Eshell does not have INSIDE_EMACS in its environment (unlike M-x shell)
which I think is a bug as it breaks the behaviour of programs that make
provisions for Emacs being used as a shell.

See
https://lists.gnu.org/archive/html/guix-devel/2020-02/msg00029.html
for a discussion.

Would it be possible to export this variable with Eshell?  Thanks!