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: https://review.openstack.org/121365

Closes-Bug: 1343604
Closes-Bug: 1345233
SecurityImpact

Change-Id: I3b49b1d667f6ade9ae3f6765d735440a3e838917