Fix Bug#31704. Do not merge

* lisp/net/tramp.el (tramp-eshell-directory-change):
Use `path-separator' as it does eshell.  (Bug#31704)
1 job for emacs-26 in 9 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #400
test

00:00:09

 
Name Stage Failure
failed
test Test There has been a runner system failure, please try again
Running with gitlab-runner 11.4.2 (cf91d5e1)
on gitlab-runner-docker cff9d373
Using Docker executor with image debian:stretch ...
Pulling docker image debian:stretch ...
Using docker image sha256:de8b49d4b0b316649307dcdda2ca0c6127f8ccdaa9c3fda6fdb21cb237cfafd8 for debian:stretch ...
ERROR: Job failed (system failure): Error response from daemon: open /var/run/docker/libcontainerd/containerd/76d31f63e1b7b3789110d4a0af864f0a8b0ba97f26927727639259a1afd7b810/init/shim-log.json: no such file or directory (executor_docker.go:1015:1s)