Sync process utils from oslo

This patch backports the missing change to fix ssh_execute password leak

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The sync pulls in the following changes:

105169f8 - Mask passwords in exceptions and error messages (SSH)
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Closes-Bug: 1377981
Change-Id: Ie0caf32469126dd9feb44867adf27acb6e383958
Merge "Sync process utils from oslo" into stable/icehouse