autotest/virt-test — pull request #1658 by yumingfei (2014-05-09 02:48:44+00:00)
Title: virttest.env_process: Fix bug of postprocess_image.

When VM image cannot be found, image.info() will return None.
Then postprocess_image will raise following exception:
raise virt_vm.VMError("Failures occurred while postprocess:%s" % err)
VMError: Failures occurred while postprocess:
Postprocess: 'NoneType' object has no attribute 'splitlines'
and test will be failed(None of testcase's business).
So check it before splitlines().

Signed-off-by: Yu Mingfei