use CommandPath.name

At the moment, CommandPath.name is initialized, but its only use as a
third string argument to OSError() is ignored.

Change-Id: I1f47b262d463a71b0438648201854cb6556355d8
Signed-off-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/10830
Reviewed-by: Yeela Kaplan <ykaplan@redhat.com>