Revert "[testrunner] catch unforeseen exceptions"

This reverts commit 101fd4dd.

Reason for revert: Uncaught exception in the recipe API https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Linux/29928

Original change's description:
> [testrunner] catch unforeseen exceptions
> 
> Testrunner doesn't catch exceptions except TestRunnererror, KeyboardInterrupt.
> 
> Unforeseen exceptions should fail the CI step.
> 
> This CL returns an error exit code for uncaught exceptions.
> 
> R=​machenbach@chromium.org
> CC=​yangguo@chromium.org,sergiyb@chromium.org
> 
> Bug: v8:8731
> Change-Id: I7fb20dad4a3eea29f1dfa87ef91d45381ee08692
> Reviewed-on: https://chromium-review.googlesource.com/c/1434034
> Commit-Queue: Tamer Tas <tmrts@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#59278}

TBR=machenbach@chromium.org,tmrts@chromium.org

Change-Id: Ia2b661c1a71d1799693383bc942a9a1d47668b24
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:8731
Reviewed-on: https://chromium-review.googlesource.com/c/1449692Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59282}

tools/testrunner/base_runner.py

@@ -10,7 +10,6 @@ import optparse
 import os
 import shlex
 import sys
-import traceback
 
 
 # Add testrunner to the path.
@@ -267,13 +266,9 @@ class BaseTestRunner(object):
                                             self.mode_name))
       return self._do_execute(tests, args, options)
     except TestRunnerError:
-      traceback.print_exc()
       return utils.EXIT_CODE_INTERNAL_ERROR
     except KeyboardInterrupt:
       return utils.EXIT_CODE_INTERRUPTED
-    except Exception:
-      traceback.print_exc()
-      return utils.EXIT_CODE_INTERNAL_ERROR
     finally:
       command.tear_down()
 

tools/unittests/run_tests_test.py

@@ -401,6 +401,13 @@ class SystemTest(unittest.TestCase):
       self.assertIn('Failed to load build config', result.stdout, result)
       self.assertEqual(5, result.returncode, result)
 
+  def testGNOption(self):
+    """Test using gn option, but no gn build folder is found."""
+    with temp_base() as basedir:
+      # TODO(machenbach): This should fail gracefully.
+      with self.assertRaises(OSError):
+        run_tests(basedir, '--gn')
+
   def testInconsistentMode(self):
     """Test failing run when attempting to wrongly override the mode."""
     with temp_base() as basedir: