Python Kivy - Why is Buildozer failing to push pro

Question

I'm trying to run a simple Kivy testapp on Android, but I'm having problems getting Buildozer to build and push the APK to my phone. I'm running it inside a Linux (Ubuntu 64-bit) virtual machine; my host machine runs Windows 10. I have installed all prerequisites that I know of: zlib1g-dev, cython, openjdk-8-jdk, git, pip.

I'm trying to run "buildozer android debug deploy run" as per the Kivy documentation's instructions and it seems like Buildozer gets pretty far into the process, but unfortunately it crashes with the following error:

a busy cat http://forumbilder.se/ECIOO/buildozer-error.png

I have no idea what this error message means and thus have no clue how to address it. Help would be appreciated, thanks.