Sync latest process and str utils from oslo

This backport the necessary changes to fix both issues:
* Make execute method clean password in exception
* Make sure mask_password works properly

Backport in oslo-incubator: 4cf1a2a158f7c3c21799bf2e6ba0e7b5fbc25d62

Closes-Bug: 1343604
Closes-Bug: 1345233
SecurityImpact

Change-Id: I3b49b1d667f6ade9ae3f6765d735440a3e838917
Merge "Sync latest process and str utils from oslo" into stable/havana