can't finish a sysupgrade on Turris omnia (OpenWrt-1907)

[SvenRoederer]

Bug report

What is the expected behaviour? I flashed the "omnia-medkit" via Rescue-mode and SSHed into it. when running sysupgrade freifunk-berlin-dev-daily-1907-ac7281549b-mvebu-cortexa9-cznic_turris-omnia-sysupgrade.img.gz it fails with zcat error. Doing the same procedure with the original OWrt18.06 images will work, using the orginal owrt19.07 snapshots fails too.

Firmware Version: dev-daily-1907-ac7281549b