Stop vendoring pluggy

.coveragerc

@@ -4,4 +4,3 @@ omit =
     *standalonetemplate.py
     # oldinterpret could be removed, as it is no longer used in py26+
     *oldinterpret.py
-    vendored_packages

_pytest/config.py

@@ -14,7 +14,7 @@
 import _pytest._code
 import _pytest.hookspec  # the extension point definitions
 import _pytest.assertion
-from _pytest._pluggy import PluginManager, HookimplMarker, HookspecMarker
+from pluggy import PluginManager, HookimplMarker, HookspecMarker
 from _pytest.compat import safe_str
 
 hookimpl = HookimplMarker("pytest")
@@ -165,7 +165,7 @@ def _prepareconfig(args=None, plugins=None):
 
 class PytestPluginManager(PluginManager):
     """
-    Overwrites :py:class:`pluggy.PluginManager <_pytest.vendored_packages.pluggy.PluginManager>` to add pytest-specific
+    Overwrites :py:class:`pluggy.PluginManager <pluggy.PluginManager>` to add pytest-specific
     functionality:
 
     * loading plugins from the command line, ``PYTEST_PLUGIN`` env variable and
@@ -203,7 +203,7 @@ def addhooks(self, module_or_class):
         """
         .. deprecated:: 2.8
 
-        Use :py:meth:`pluggy.PluginManager.add_hookspecs <_pytest.vendored_packages.pluggy.PluginManager.add_hookspecs>`
+        Use :py:meth:`pluggy.PluginManager.add_hookspecs <PluginManager.add_hookspecs>`
         instead.
         """
         warning = dict(code="I2",

_pytest/hookspec.py

@@ -1,6 +1,6 @@
 """ hook specifications for pytest plugins, invoked from main.py and builtin plugins.  """
 
-from _pytest._pluggy import HookspecMarker
+from pluggy import HookspecMarker
 
 hookspec = HookspecMarker("pytest")
 

_pytest/python.py

@@ -15,7 +15,7 @@
 from _pytest.config import hookimpl
 
 import _pytest
-import _pytest._pluggy as pluggy
+import pluggy
 from _pytest import fixtures
 from _pytest import main
 from _pytest.compat import (

_pytest/terminal.py

@@ -13,8 +13,7 @@
 import sys
 import time
 import platform
-
-import _pytest._pluggy as pluggy
+import pluggy
 
 
 def pytest_addoption(parser):