Hello @DannyPM,
I will take it from the other side. How did you manage to install the package tcpdump-mini? I can see that the package - tcpdump by default has been provided for a long time, so this is not a regression in this update. I could not install the mini variant. Well, I can, but I need to try harder. 
See my output:
root@turris:~# opkg update
root@turris:~# opkg install tcpdump-mini
Installing tcpdump-mini (4.9.3-2) to root...
Downloading https://repo.turris.cz/hbs/omnia/packages/base/tcpdump-mini_4.9.3-2_arm_cortex-a9_vfpv3-d16.ipk
Collected errors:
* check_data_file_clashes: Package tcpdump-mini wants to install file /usr/sbin/tcpdump
But that file is already provided by package * tcpdump
* opkg_install_cmd: Cannot install package tcpdump-mini.
root@turris:~# opkg remove tcpdump
Removing package tcpdump from root...
WARNING: You probably just removed a package that was installed as part of a user list or the basic system. This package will return durring the next updater run. We suggest you disable the user list instead.
Well, if you don’t need to use the minimal variant explicitly, I suggest removing it and using the full-featured variant.