When the first parametrized test takes a bit longer than usual, the zone
transfer in ns3 may succeed before the second parametrized test is even
started, and then watch_log_from_here() won't find the "Transfer status:
success" message in the named log. Using watch_log_from_start() instead
makes sure the test is more stable.
(cherry picked from commit 283a7ab17d)
Michal Nowak
195b892bde