tests: removed ReportedTest exception

The only call site called addFailure before raising, which is
exactly what the failure exception handler does. So this
complexity is not needed.

We have test coverage of this "server failed to start" scenario
and nothing appeared to change.

tests/run-tests.py

@@ -717,8 +717,6 b' class Test(unittest.TestCase):'
                 # test we "ran", but we want to exclude skipped tests
                 # from those we count towards those run.
                 result.testsRun -= 1
-            except ReportedTest as e:
-                pass
             except self.failureException as e:
                 # This differs from unittest in that we don't capture
                 # the stack trace. This is for historical reasons and
@@ -1479,9 +1477,6 b' class TTest(Test):'
 
 iolock = threading.RLock()
 
-class ReportedTest(Exception):
-    """Raised to indicate that a test already reported."""
-
 class TestResult(unittest._TextTestResult):
     """Holds results when executing via unittest."""
     # Don't worry too much about accessing the non-public _TextTestResult.
@@ -1578,10 +1573,8 b' class TestResult(unittest._TextTestResul'
                 servefail, lines = getdiff(expected, got,
                                            test.refpath, test.errpath)
                 if servefail:
-                    self.addFailure(
-                        test,
+                    raise test.failureException(
                         'server failed to start (HGPORT=%s)' % test._startport)
-                    raise ReportedTest('server failed to start')
                 else:
                     self.stream.write('\n')
                     for line in lines: