fix repo handling on SDCard/USB-OTG
This makes the USB-OTG/SDCard mirror/repo support work on android-29+, and improves the general UX. Details in the commit messages. This builds upon @cde's work in !870 (merged)
Edited by Hans-Christoph Steiner
This makes the USB-OTG/SDCard mirror/repo support work on android-29+, and improves the general UX. Details in the commit messages. This builds upon @cde's work in !870 (merged)