Can you please reproduce bugs with the latest version of QEMU, i.e. currently v2.11 ? Old versions like 2.5 are not supported by the upstream QEMU project anymore, and bugs from such old versions might have been fixed already. (Otherwise, if you're only interested in the Ubuntu binary, please open a bug against the Ubuntu QEMU package instead)
Can you please reproduce bugs with the latest version of QEMU, i.e. currently v2.11 ? Old versions like 2.5 are not supported by the upstream QEMU project anymore, and bugs from such old versions might have been fixed already. (Otherwise, if you're only interested in the Ubuntu binary, please open a bug against the Ubuntu QEMU package instead)