Bug#891363: Acknowledgement (Diffoscope crashes when cleaning non-writeable temporary files/dirs)

[michal marzuchowski]

The issue can be reproduced by comparing two different official images 
from https://nixos.org/nixos/download.html, e.g. x86_64 and i686.
https://d3g5gsiof5omrk.cloudfront.net/nixos/17.09/nixos-17.09.3047.8bce347f02f/nixos-minimal-17.09.3047.8bce347f02f-x86_64-linux.iso
https://d3g5gsiof5omrk.cloudfront.net/nixos/17.09/nixos-17.09.3047.8bce347f02f/nixos-minimal-17.09.3047.8bce347f02f-i686-linux.iso

It takes over 1h to compare those 337M ISOs. I guess that minimal case 
would be non-writeable file in non-writeable directory in squashfs in 
ISO image. Neither tar nor squashfs alone triggered the issue (i.e. 
without ISO image).