various fixes from first test runs

Change-Id: Ifa5a780dc0123aa84273c57c726c8c1bea563495
diff --git a/src/osmo_gsm_tester/trial.py b/src/osmo_gsm_tester/trial.py
index a938971..0a882f8 100644
--- a/src/osmo_gsm_tester/trial.py
+++ b/src/osmo_gsm_tester/trial.py
@@ -50,7 +50,7 @@
 
     def __init__(self, trial_dir):
         self.path = trial_dir
-        self.set_name(self.path)
+        self.set_name(os.path.basename(self.path))
         self.set_log_category(log.C_TST)
         self.dir = util.Dir(self.path)
         self.inst_dir = util.Dir(self.dir.child('inst'))
@@ -133,7 +133,7 @@
     def get_inst(self, bin_name):
         bin_tar = self.has_bin_tar(bin_name)
         if not bin_tar:
-            return None
+            raise RuntimeError('No such binary available: %r' % bin_name)
         inst_dir = self.inst_dir.child(bin_name)
 
         if os.path.isdir(inst_dir):