Hrm.. if the second line shows "set -ex" then running os-prober should produce a lot of debug output showing every line of the script that is executed. Oh, try running it yourself instead of letting the installer do it.
Hrm.. if the second line shows "set -ex" then running os-prober should produce a lot of debug output showing every line of the script that is executed. Oh, try running it yourself instead of letting the installer do it.