/usr/share/bug/xdg-utils/script is in xdg-utils 1.1.2-1ubuntu2.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 | #!/bin/sh
set -e
echo "Desktop environment: XDG_CURRENT_DESKTOP=$XDG_CURRENT_DESKTOP" >&3
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