Merge pull request 'Make tar archives deterministic' (#693) from repbuilds-additional into trunk

Reviewed-on: #693
Reviewed-by: Dan Ballard <dan@openprivacy.ca>

.drone.yml

@@ -57,7 +57,8 @@ steps:
       - mkdir -p deploy/cwtch
       - cp -r build/linux/x64/release/bundle/* deploy/cwtch
       - cd deploy
-      - tar -czf cwtch-`cat ../VERSION`.tar.gz cwtch
+      # Tar archives need a few tricks to make this deterministic, see https://reproducible-builds.org/docs/archives/
+      - tar --sort=name --mtime=`cat COMMIT_DATE` --owner=0 --group=0 --numeric-owner --pax-option=exthdr.name=%d/PaxHeaders/%f,delete=atime,delete=ctime -czf cwtch-`cat ../VERSION`.tar.gz cwtch
       - rm -r cwtch
 
   - name: linux-ui-tests