Properly re-raise exceptions in proxy_logging
Properly re-raise exceptions in proxy_logging

Previously, this could encounter TypeErrors, presumably because
sys.exc_clear() was called somewhere in the block of code between
catching the exception and re-raising.

Related-Bug: 1181146
Change-Id: Iadeea3f61e70bf83dc0eb063fdb27edd16f3ca32

dencaval/swift,openstack/swift,rackerlabs/swift,clayg/swift,bradleypj823/swift,clayg/swift,nadeemsyed/swift,clayg/swift,Akanoa/swift,redbo/swift,bkolli/swift,openstack/swift,dencaval/swift,Em-Pan/swift,smerritt/swift,daasbank/swift,hbhdytf/mac2,Em-Pan/swift,nadeemsyed/swift,hbhdytf/mac2,williamthegrey/swift,smerritt/swift,zackmdavis/swift,clayg/swift,mjwtom/swift,matthewoliver/swift,mjzmjz/swift,wenhuizhang/swift,thiagodasilva/swift,larsbutler/swift,hbhdytf/mac,psachin/swift,iostackproject/IO-Bandwidth-Differentiation,notmyname/swift,bouncestorage/swift,tipabu/swift,levythu/swift,redbo/swift,swiftstack/swift,iostackproject/IO-Bandwidth-Differentiation,aerwin3/swift,openstack/swift,hbhdytf/mac2,gold3bear/swift,larsbutler/swift,matthewoliver/swift,redhat-openstack/swift,takeshineshiro/swift,nadeemsyed/swift,hurricanerix/swift,bradleypj823/swift,rackerlabs/swift,notmyname/swift,revoer/keystone-8.0.0,takeshineshiro/swift,williamthegrey/swift,hurricanerix/swift,openstack/swift,notmyname/swift,shibaniahegde/OpenStak_swift,hbhdytf/mac,smerritt/swift,aerwin3/swift,wenhuizhang/swift,mjzmjz/swift,nadeemsyed/swift,matthewoliver/swift,psachin/swift,swiftstack/swift,tipabu/swift,psachin/swift,prashanthpai/swift,Seagate/swift,smerritt/swift,thiagodasilva/swift,hurricanerix/swift,tipabu/swift,gold3bear/swift,hurricanerix/swift,bouncestorage/swift,bkolli/swift,swiftstack/swift,mjwtom/swift,matthewoliver/swift,tipabu/swift,zackmdavis/swift,Akanoa/swift,revoer/keystone-8.0.0,notmyname/swift,Seagate/swift,psachin/swift,daasbank/swift,shibaniahegde/OpenStak_swift,prashanthpai/swift,hbhdytf/mac2,redhat-openstack/swift,levythu/swift