Log Message:
Update databases/py-barman to 1.4.1.

Version 1.4.1 - 05 May 2015
  * Fix for WAL archival stop working if first backup is EMPTY
    (Closes: #64)
  * Fix exception during error handling in Barman recovery (Closes:
    #65)
  * After a backup, limit cron activity to WAL archiving only
    (Closes: #62)
  * Improved robustness and error reporting of the backup delete
    command (Closes: #63)
  * Fix computation of WAL production ratio as reported in the
    show-backup command
  * Improved management of xlogb file, which is now correctly fsynced
    when updated. Also, the rebuild-xlogdb command now operates on a
    temporary new file, which overwrites the main one when finished.
  * Add unit tests for dateutil module compatibility
  * Modified Barman version following PEP 440 rules and added support
    of tests in Python 3.4