As a seasoned user I know zypper does the right thing when configured properly. Some call it blissful childish self-assurance.
However unattended background distribution upgrades work like a charm. I safely ignore trivial issues as the above one:
6700k:~ # ssh erlangen journalctl -q -g libvo-amrwbenc0
Sep 07 16:06:32 erlangen zypper[16852]: libvo-amrwbenc0
Sep 07 16:06:32 erlangen zypper[16852]: libvo-amrwbenc0
Sep 07 16:06:34 erlangen zypper[16852]: In cache libvo-amrwbenc0-0.1.3+5-1.2.x86_64.rpm (1/1), 78.1 KiB
Sep 07 16:06:34 erlangen [RPM][17752]: erase libvo-amrwbenc0-0.1.3-1699.1.pm.85.x86_64: success
Sep 07 16:06:34 erlangen [RPM][17752]: install libvo-amrwbenc0-0.1.3+5-1.2.x86_64: success
Sep 07 16:06:34 erlangen [RPM][17752]: erase libvo-amrwbenc0-0.1.3-1699.1.pm.85.x86_64: success
Sep 07 16:06:34 erlangen [RPM][17752]: install libvo-amrwbenc0-0.1.3+5-1.2.x86_64: success
Sep 07 16:06:34 erlangen zypper[16852]: (1/1) Installing: libvo-amrwbenc0-0.1.3+5-1.2.x86_64 [...done]
6700k:~ #