run-tests: don't trap exceptions in Test.runTest()

Exceptions are all handled in Test.run(). This code was redundant since
the unittest test wrapper class was merged into Test.

tests/run-tests.py

@@ -485,15 +485,10 b' class Test(unittest.TestCase):'
 
         vlog('# Test', self.name)
 
-        try:
             ret, out = self._run(replacements, env)
             self._finished = True
             self._ret = ret
             self._out = out
-        except KeyboardInterrupt:
-            raise
-        except Exception, e:
-            return self.fail('Exception during execution: %s' % e, 255)
 
         def describe(ret):
             if ret < 0: