Build python-docker for xenial

Change-Id: I0c968abb1769f15667af669b87d5df737e45bcd4
diff --git a/jenkins/client/job/debian/packages/extra.yml b/jenkins/client/job/debian/packages/extra.yml
index e51354a..15d0bc4 100644
--- a/jenkins/client/job/debian/packages/extra.yml
+++ b/jenkins/client/job/debian/packages/extra.yml
@@ -53,6 +53,8 @@
               dist: xenial
             - package: python-geventhttpclient
               dist: xenial
+            - package: python-docker
+              dist: xenial
             - package: python-consistent-hash
               dist: xenial
             - package: libipfix