Merge pull request #4417 from nishanttotla/update_swarm_v1.2.9

Update swarm v1.2.9

library/swarm

@@ -5,5 +5,5 @@ Maintainers: Alexandre Beslic <[email protected]> (@abronan),
              Victor Vieux <[email protected]> (@vieux)
 GitRepo: https://github.com/docker/swarm-library-image.git
 
-Tags: 1.2.8, latest
-GitCommit: 741c78fb0287dc0850f5f131e099610a7acc2bf9
+Tags: 1.2.9, latest
+GitCommit: a2a08d733833327354b5d3336ffbd19e4f369a2d