Confused web diff when you edit a file inside the archive

[lkocman]

Hello team,

I've noticed that if I amend/update etc/d-installer.yaml inside default.tar.xz, then OBS incorrectly shows that I've placed the file into the "top level directory" and displays etc and etc/d-installer.yaml as removed. While in fact I've just edited the file.

See diff in https://build.opensuse.org/request/show/1069188

So the diff looks as follows
+d-installer.yaml
-etc/
-etc/d-installer.yaml

while it should be

-/+etc/d-installer.yaml

This is confusing to reviewers