teuthology/suite: initialize lua prng using run's seed

When a script may use Lua's prng, we want it to produce the same sequence
during a rerun.

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>

teuthology/suite/merge.py

@@ -115,6 +115,8 @@ def config_merge(configs, suite_name=None, **kwargs):
     the entire job (config) from the list.
     """
 
+    seed = kwargs.get('seed')
+    new_script = L.eval(f'local math = require"math"; math.randomseed({seed});')
     new_script = L.eval('new_script')
     yaml_cache = {}
     for desc, paths in configs:

teuthology/suite/run.py

@@ -591,6 +591,7 @@ def schedule_suite(self):
             filter_out=self.args.filter_out,
             filter_all=self.args.filter_all,
             filter_fragments=self.args.filter_fragments,
+            seed=self.args.seed,
             suite_name=suite_name))
 
         if self.args.dry_run: