Simplify the code in s3api
Simplify the code in s3api

At least now you know that the "with" clause isn't modifying
a self.something behind your back.

The affected part was added when migrating from swift3 to s3api.
As a bonus, the patch makes the code slightly more similar to
the original.

Change-Id: Id4bfbaf971e3a08fdf9d0ef8d7373bb36c298682

tipabu/swift,tipabu/swift,openstack/swift,tipabu/swift,tipabu/swift,swiftstack/swift,openstack/swift,swiftstack/swift,swiftstack/swift,openstack/swift,openstack/swift