avoid prepend to register api as it's redundant wrt to hooks

--HG--
branch : plugin_no_pytest

_pytest/main.py

@@ -510,7 +510,7 @@ class Session(FSCollector):
     def __init__(self, config):
         FSCollector.__init__(self, config.rootdir, parent=None,
                              config=config, session=self)
-        self.config.pluginmanager.register(self, name="session", prepend=True)
+        self.config.pluginmanager.register(self, name="session")
         self._testsfailed = 0
         self.shouldstop = False
         self.trace = config.trace.root.get("collection")
@@ -521,10 +521,12 @@ class Session(FSCollector):
     def _makeid(self):
         return ""
 
+    @pytest.mark.tryfirst
     def pytest_collectstart(self):
         if self.shouldstop:
             raise self.Interrupted(self.shouldstop)
 
+    @pytest.mark.tryfirst
     def pytest_runtest_logreport(self, report):
         if report.failed and not hasattr(report, 'wasxfail'):
             self._testsfailed += 1