Sync latest process and str utils from oslo

This sync required changes to fix these issues:
* Make execute method clean password in exception
* Make sure mask_password works properly

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The sync pulls in the following changes (newest to oldest):

6a60f842 - Mask passwords in exceptions and error messages (SSH)
63c99a0f - Mask passwords in exceptions and error messages
66142c34 - Make strutils.mask_password more secure

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Closes-Bug: 1343604
Closes-Bug: 1345233
SecurityImpact

Change-Id: I3b49b1d667f6ade9ae3f6765d735440a3e838917
Merge "Sync latest process and str utils from oslo"