Comment 23 for bug 1717040

@cyan4973, may I change your first test case into something that won't involve a download/build/install cycle? I was thinking about just using the 0.5.1 version in xenial to try to decompress the 1.3.1 compressed file I created in the test I just added to the bug description. Something like this:

"""
* Downgrade zstd back to xenial's original version:

$ sudo apt install zstd=0.5.1-1

* Try to decompress the zst file created with the 1.3.1 version from the previous test. It should fail to recognize the format:
$ zstd -d snap.1.3.1.zst -o /dev/null
zstd: /dev/null already exists; do you wish to overwrite (y/N) ? y
zstd: snap.1.3.1.zst: not in zstd format
"""

Would that be ok, and still be in the spirit of this update?