[paperkey] Always output "interrupt"

[Damien Cassou]

Hi,

The output of paperkey is just "interrupt" instead of being a printable
output. I've tried to use paperkey on 2 different main private keys and
failed twice. I tried with both the Fedora package and from paperkey's
source. Same result in every case.

System:
- Fedora 28
- gpg (GnuPG) 2.2.8, libgcrypt 1.8.3

Keys:
- key1: ed25519
- key2: rsa4096

Command:
$ gpg2 --export-secret-key "FooBar" | paperkey -vvvv
interrupt
$

Best

-- 
Damien Cassou
http://damiencassou.seasidehosting.st

"Success is the ability to go from one failure to another without
losing enthusiasm." --Winston Churchill