pdb: do not raise outcomes.Exit with quit in debug

changelog/4968.bugfix.rst

@@ -0,0 +1 @@
+The pdb ``quit`` command is handled properly when used after the ``debug`` command.

src/_pytest/debugging.py

@@ -128,8 +128,15 @@ def do_continue(self, arg):
                 do_c = do_cont = do_continue
 
                 def set_quit(self):
+                    """Raise Exit outcome when quit command is used in pdb.
+
+                    This is a bit of a hack - it would be better if BdbQuit
+                    could be handled, but this would require to wrap the
+                    whole pytest run, and adjust the report etc.
+                    """
                     super(_PdbWrapper, self).set_quit()
-                    outcomes.exit("Quitting debugger")
+                    if cls._recursive_debug == 0:
+                        outcomes.exit("Quitting debugger")
 
                 def setup(self, f, tb):
                     """Suspend on setup().

testing/test_pdb.py

@@ -954,3 +954,30 @@ def test_2():
     rest = child.read().decode("utf8")
     assert "no tests ran" in rest
     TestPDB.flush(child)
+
+
+def test_pdb_quit_after_debug(testdir):
+    p1 = testdir.makepyfile(
+        mytest="""
+        def foo():
+            pass
+
+        def test_1():
+            __import__('pdb').set_trace()
+    """
+    )
+    child = testdir.spawn_pytest(str(p1))
+    child.expect(r"\n\(Pdb")
+    child.sendline("debug foo()")
+    child.expect("ENTERING RECURSIVE DEBUGGER")
+    child.expect(r"\n\(\(Pdb")
+    child.sendline("q")
+    child.expect("LEAVING RECURSIVE DEBUGGER")
+    assert b"Quitting debugger" not in child.before
+    child.sendline("q")
+    rest = child.read().decode("utf8")
+    # NOTE: there should be less trailing newlines with this probably, but
+    # this tests the current behavior.
+    assert "\r\nExit: Quitting debugger\r\n\r\n\r\n"
+    assert " Quitting debugger !" in rest
+    assert "= no tests ran in " in rest