switch-branch and opkg: opkg postinst script fails to verify/fix branch setting because of locked opkg
When opkg is updated it overrides `/etc/opkg/distfeeds.conf`. `postinst` script contains for that reason call to `switch-branch --verify`. Problem is that this call fails when called as part of updater process because opkg is unable to lock its lock.
We should drop all usage of opkg in `switch-branch` with exception of installations because of that.
issue