Merged #2082 prematurely. @lzybkr brought to my attention that his concern wasn't addressed.

https://github.com/PowerShell/PowerShell/blob/master/tools/appimage.sh#L41

Relies on

https://github.com/probonopd/AppImages/raw/e05cbebc62c86f8c602d74d9050bbfbf10df1c69/functions.sh 

which internally gets and executes other scripts.

If any of these scripts are compromised, we'll run arbitrary code as part of our publishing pipeline.
We need to resolve this vulnerability before we start publishing appimages.

CC @raghushantha @andschwa @probonopd