Plugin test: Fix incorrect NAME_CONFLICT check in test_volume_replication()
Plugin test: Fix incorrect NAME_CONFLICT check in test_volume_replication()

 * If certain plugin didn't raise LsmError on NAME_CONFLICT for
   volume_create(), plugin_test.py will incorrectly treat it as PASS.
   This patch fixed it by using a error_num variable to checking
   NAME_CONFLICT.

Signed-off-by: Gris Ge <e24f3acbe39bf94f92e8af3c48f8852106ad5ad7@redhat.com>

tasleson/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,jumitche/libstoragemgmt,lazy404/libstoragemgmt,tasleson/libstoragemgmt,cathay4t/libstoragemgmt,libstorage/libstoragemgmt,lazy404/libstoragemgmt,tasleson/libstoragemgmt,cathay4t/libstoragemgmt,lazy404/libstoragemgmt,jumitche/libstoragemgmt,joehandzik/libstoragemgmt,tasleson/libstoragemgmt,cathay4t/libstoragemgmt,joehandzik/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,tasleson/libstoragemgmt,libstorage/libstoragemgmt,cathay4t/libstoragemgmt,HP-Scale-out-Storage/libstoragemgmt,jumitche/libstoragemgmt,libstorage/libstoragemgmt,jumitche/libstoragemgmt,libstorage/libstoragemgmt,cathay4t/libstoragemgmt,lazy404/libstoragemgmt,jumitche/libstoragemgmt,joehandzik/libstoragemgmt,libstorage/libstoragemgmt,joehandzik/libstoragemgmt