python: fix snapshot listing bugs
python: fix snapshot listing bugs

Python exceptions are different than libvirt errors, and we had
some corner case bugs on OOM situations.

* python/libvirt-override.c (libvirt_virDomainSnapshotListNames)
(libvirt_virDomainSnapshotListChildrenNames): Use correct error
returns, avoid segv on OOM, and avoid memory leaks on error.

jardasgit/libvirt,zhlcindy/libvirt-1.1.4-maintain,zippy2/libvirt,dumbbell/libvirt,zippy2/libvirt,VenkatDatta/libvirt,zhlcindy/libvirt-1.1.4-maintain,cbosdo/libvirt,emaste/libvirt,andreabolognani/libvirt,iam-TJ/libvirt,wiedi/libvirt,nertpinx/libvirt,emaste/libvirt,crobinso/libvirt,shugaoye/libvirt,taget/libvirt,rlaager/libvirt,novel/fbsd-libvirt,rmarwaha/libvirt1,iam-TJ/libvirt,zippy2/libvirt,jeckersb/libvirt,rmarwaha/libvirt,bjzhang/libvirt,fabianfreyer/libvirt,trainstack/libvirt,jardasgit/libvirt,novel/fbsd-libvirt,cbosdo/libvirt,novel/fbsd-libvirt,libvirt/libvirt,emaste/libvirt,wiedi/libvirt,jeckersb/libvirt,VenkatDatta/libvirt,rlaager/libvirt,emaste/libvirt,andreabolognani/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,eskultety/libvirt,rmarwaha/libvirt1,VenkatDatta/libvirt,warewolf/libvirt,crobinso/libvirt,elmarco/libvirt,andreabolognani/libvirt,rlaager/libvirt,cbosdo/libvirt,wiedi/libvirt,iam-TJ/libvirt,jeckersb/libvirt,cbosdo/libvirt,bjzhang/libvirt,libvirt/libvirt,wiedi/libvirt,andreabolognani/libvirt,zhlcindy/libvirt-1.1.4-maintain,novel/fbsd-libvirt,rmarwaha/libvirt,rlaager/libvirt,zhlcindy/libvirt-1.1.4-maintain,datto/libvirt,iam-TJ/libvirt,warewolf/libvirt,eskultety/libvirt,dumbbell/libvirt,jfehlig/libvirt,shugaoye/libvirt,elmarco/libvirt,nertpinx/libvirt,shugaoye/libvirt,olafhering/libvirt,trainstack/libvirt,datto/libvirt,trainstack/libvirt,nertpinx/libvirt,jfehlig/libvirt,rmarwaha/libvirt1,novel/fbsd-libvirt,wiedi/libvirt,wiedi/libvirt,iam-TJ/libvirt,wiedi/libvirt,jardasgit/libvirt,novel/fbsd-libvirt,trainstack/libvirt,eskultety/libvirt,crobinso/libvirt,olafhering/libvirt,bjzhang/libvirt,jeckersb/libvirt,eskultety/libvirt,olafhering/libvirt,siboulet/libvirt-openvz,nertpinx/libvirt,taget/libvirt,taget/libvirt,dumbbell/libvirt,novel/fbsd-libvirt,rmarwaha/libvirt,siboulet/libvirt-openvz,trainstack/libvirt,emaste/libvirt,trainstack/libvirt,jeckersb/libvirt,cbosdo/libvirt,elmarco/libvirt,jeckersb/libvirt,emaste/libvirt,shugaoye/libvirt,zippy2/libvirt,bjzhang/libvirt,siboulet/libvirt-openvz,crobinso/libvirt,agx/libvirt,taget/libvirt,eskultety/libvirt,fabianfreyer/libvirt,agx/libvirt,fabianfreyer/libvirt,elmarco/libvirt,emaste/libvirt,elmarco/libvirt,jeckersb/libvirt,warewolf/libvirt,warewolf/libvirt,olafhering/libvirt,agx/libvirt,VenkatDatta/libvirt,zhlcindy/libvirt-1.1.4-maintain,siboulet/libvirt-openvz,novel/fbsd-libvirt,dumbbell/libvirt,siboulet/libvirt-openvz,rmarwaha/libvirt,jfehlig/libvirt,jfehlig/libvirt,iam-TJ/libvirt,fabianfreyer/libvirt,iam-TJ/libvirt,datto/libvirt,nertpinx/libvirt,libvirt/libvirt,andreabolognani/libvirt,datto/libvirt,rmarwaha/libvirt,rmarwaha/libvirt1,agx/libvirt,jardasgit/libvirt,rmarwaha/libvirt1,trainstack/libvirt,dumbbell/libvirt,rmarwaha/libvirt1,novel/fbsd-libvirt,fabianfreyer/libvirt,warewolf/libvirt,agx/libvirt,warewolf/libvirt,taget/libvirt,libvirt/libvirt,warewolf/libvirt,rlaager/libvirt,rmarwaha/libvirt,dumbbell/libvirt,bjzhang/libvirt,shugaoye/libvirt,datto/libvirt