From https://git.joeyh.name/index.cgi/etckeeper.git/tree/update-ignore.d/01update-ignore#n110:

> \# Not currently ignored as admins tend to rely on these files.

> \#ignore "passwd-"

> \#ignore "group-"

> \#ignore "shadow-"

> \#ignore "gshadow-"

But I can't understand the reason, considering that ignoring these backup files justs leaves them there so admins can still use them. In the other hand, having the original files (e.g. `passwd`) under version control will provide admins the expected history of changes.
