tar: Unrecognized archive format from heroku slugs:download

[dentarg]

$ heroku slugs:download -a appname
Downloading... ████████████████████████▏  100% 00:00 20.3MB
tar: Unrecognized archive format
tar: Error exit delayed from previous errors.
 ▸    Command failed: tar -xf appname/slug.tar.gz -C appname
 ▸    tar: Unrecognized archive format
 ▸    tar: Error exit delayed from previous errors.
 ▸

$ file appname/slug.tar.gz
appname/slug.tar.gz: Squashfs filesystem, little endian, version 3.1, 21286731 bytes, 7778 inodes, blocksize: 131072 bytes, created: Thu Jun  7 07:46:30 2012

Maybe because app stack is cedar?

[dentarg]

Managed to extract the files with unsquashfs -f -d myfolder slug.tar.gz