It came to my attention that the ownership of /var/cache/man is not set
correctly inside the official opensuse container that is distributed via
hub.docker.com.

#> docker pull opensuse
Using default tag: latest
latest: Pulling from library/opensuse
Digest: sha256:3239da690c9c12447e0137c8a5028a64317901356167bbc6c420c9a697e1f8e0
Status: Image is up to date for opensuse:latest

#> docker run -it --rm opensuse ls -l /var/cache | grep man
drwxr-xr-x 1 root root  0 May  9  2017 man

The correct ownership should be "man:root" so that the mandb tool can work
inside that directory. Right now that is now the case.

#> mandb
mandb: warning: cannot create catdir /var/cache/man/ca
mandb: can't create a temporary filename: No such file or directory

The filesystem package defines that directory as follows:

#> cat openSUSE:Leap:42.3/filesystem/directory.list | grep "/var/cache/man"
0755 man root /var/cache/man


I'm not sure how the distribution of that official image is actually working
and at which point this problem got or gets introduced. I'm quite interested to
see how this is actually done.