Hi,

Not sure if it's due to switching to .tar.xz or to my use of 'pixz -7':

# Get the tarball:
user@debian:~$ git clone git://git.sv.gnu.org/freedink/freedink-data.git -b v1.08.20170401
user@debian:~$ cd freedink-data/
user@debian:~/freedink-data$ make dist VERSION=1.08.20170401
...
tar -c --sort=name \
  --mtime="@1491004800" \
  --owner=root --group=root --numeric-owner \
  freedink-data-1.08.20170401/ | pixz -7 > freedink-data-1.08.20170401.tar.xz
...
# reproducible source tarball (not very helpful per se... but it may help here) :
user@debian:~/freedink-data$ wget ftp.gnu.org/gnu/freedink/freedink-data-1.08.20170401.tar.xz.sig
user@debian:~/freedink-data$ gpg --verify freedink-data-1.08.20170401.tar.xz.sig
gpg: assuming signed data in 'freedink-data-1.08.20170401.tar.xz'
gpg: Signature made sam. 01 avril 2017 22:12:26 CEST
gpg:                using RSA key 42273C1AE37FC4347CF079128FF1CB6E8D89059F
gpg: Good signature from "Sylvain Beucler <beuc@beuc.net>" [unknown]
...
# or: wget ftp.gnu.org/gnu/freedink/freedink-data-1.08.20170401.tar.xz  directly

# Call pristine-tar (long):
user@debian:~/freedink-data$ pristine-tar commit freedink-data-1.08.20170401.tar.xz v1.08.20170401
pristine-xz failed to reproduce build of freedink-data-1.08.20170401.tar.xz
(Please file a bug report.)
pristine-tar: command failed: pristine-xz --no-verbose --no-debug --no-keep gendelta freedink-data-1.08.20170401.tar.xz /tmp/pristine-tar.ncEmWw6MEa/wrapper
pristine-tar: failed to generate delta


Previous .tar.tz tarballs of freedink-data are available in the
'pristine-tar' branch.

I believe the problem is due to the use of pigz without -t.  By
default, when compressing a tar file, pixz appends a compressed block
containing an index of the tar contents.  pristine-xz does not
currently have a way to preserve this block.

I have submitted a patch[1] as part of a merge request[2] which fixes
this issue.

Cheers,
Kevin

1.  https://salsa.debian.org/debian/pristine-tar/commit/9ffc6b475fc6cf4e98b102133b2ee63127cc4208?merge_request_iid=3
2.  https://salsa.debian.org/debian/pristine-tar/merge_requests/3