virttest.utils_test: Fix python 2.4 incompatibility

Every now and then we sneak a try/except/finally block
in the code, even though it's 2.4 illegal. Let's fix
it.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
virttest/qemu: PEP8 fixes

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>