Cause: Parallel installable python-webob1.2 isn't found by keystoneclient.
Consequence: Importing python-webob from keystoneclient fails with stacktrace. This also applies to applications using keystoneclient such as Swift proxy.
Fix: Properly look for python-webob1.2 and require python-webob1.2 instead of python-webob.
Result: The keystoneclient is able to import python-webob1.2 independently from other installed versions.