DvcsScheduler job is not running, stops the scheduled synchronisation

Symptoms

After upgrading to JIRA 6.3-OD1, the DvcsScheduler job is not running.

This stops the hourly scheduled synchronization.

Commits and Pull requests sync could still be triggered by Bitbucket/GitHub webhook. However, for systems which upgrade from an earlier version to 1.4.15 and later and have not changed the DVCS accounts, pull requests webhooks are not created, thus pull requests would not be synchronized.

This issue does not affect JIRA 6.2.1 BTF.

Workaround

As a workaround, manually clicking on the sync icon on the DVCS Accounts page would run the synchronization, though each click does it once only.