Derive outcomes.exit.Exception from SystemExit instead of KeyboardInterrupt

This is required for properly getting out of pdb, where
KeyboardInterrupt is caught in py36 at least.

Ref: pytest-dev#1865 (comment)

Author: blueyed

src/_pytest/main.py

@@ -205,7 +205,8 @@ def wrap_session(config, doit):
             raise
         except Failed:
             session.exitstatus = EXIT_TESTSFAILED
-        except KeyboardInterrupt:
+        # except KeyboardInterrupt:
+        except (KeyboardInterrupt, exit.Exception):
             excinfo = _pytest._code.ExceptionInfo.from_current()
             exitstatus = EXIT_INTERRUPTED
             if initstate <= 2 and isinstance(excinfo.value, exit.Exception):

src/_pytest/outcomes.py

@@ -49,21 +49,21 @@ class Failed(OutcomeException):
     __module__ = "builtins"
 
 
-class Exit(KeyboardInterrupt):
+class Exit(SystemExit):
     """ raised for immediate program exits (no tracebacks/summaries)"""
 
     def __init__(self, msg="unknown reason", returncode=None):
         self.msg = msg
         self.returncode = returncode
-        KeyboardInterrupt.__init__(self, msg)
+        SystemExit.__init__(self, msg)
 
 
 # exposed helper methods
 
 
 def exit(msg, returncode=None):
     """
-    Exit testing process as if KeyboardInterrupt was triggered.
+    Exit testing process as if SystemExit was triggered.
 
     :param str msg: message to display upon exit.
     :param int returncode: return code to be used when exiting pytest.

testing/test_runner.py

@@ -553,7 +553,7 @@ def test_outcomeexception_passes_except_Exception():
 def test_pytest_exit():
     with pytest.raises(pytest.exit.Exception) as excinfo:
         pytest.exit("hello")
-    assert excinfo.errisinstance(KeyboardInterrupt)
+    assert excinfo.errisinstance(pytest.exit.Exception)
 
 
 def test_pytest_fail():