Merge lp:~cjwatson/launchpad-buildd/lxd-no-gzip into lp:launchpad-buildd

[Colin Watson]

Don't gzip LXD tarballs. Python's gzip is apparently very slow.

This takes unpack-chroot from about 1m59s to about 42s on my laptop.

[William Grant (wgrant)]

review: Approve (code)

=== modified file 'lpbuildd/target/lxd.py'
--- lpbuildd/target/lxd.py	2017-08-29 12:51:42 +0000
+++ lpbuildd/target/lxd.py	2017-08-30 13:01:02 +0000
@@ -158,7 +158,7 @@
         with io.BytesIO() as target_file:
             with tarfile.open(name=tarball_path, mode="r") as source_tarball:
                 with tarfile.open(
-                        fileobj=target_file, mode="w:gz") as target_tarball:
+                        fileobj=target_file, mode="w") as target_tarball:
                     self._convert(source_tarball, target_tarball)
 
             image = self.client.images.create(