fixed circular imports by reverting a few py.test -> pytest substitions.

CHANGELOG

@@ -5,12 +5,13 @@ UNRELEASED
   trying to import from collections.abc which causes problems for py27/cx_freeze.
   Thanks Wolfgang L. for reporting and tracking it down.
 
-- fixed docs and code to use "pytest" instead of "py.test" everywhere.
+- fixed docs and code to use "pytest" instead of "py.test" almost everywhere.
   Thanks Jurko Gospodnetic for the complete PR.  
 
 - fix issue425: mention at end of "py.test -h" that --markers
   and --fixtures work according to specified test path (or current dir)
 
+
 2.5.1
 -----------------------------------
 

_pytest/config.py

@@ -1,7 +1,7 @@
 """ command line options, ini-file and conftest.py processing. """
 
 import py
-import pytest
+# DON't import pytest here because it causes import cycle troubles
 import sys, os
 from _pytest import hookspec # the extension point definitions
 from _pytest.core import PluginManager
@@ -817,7 +817,8 @@ class Config(object):
                 raise KeyError(name)
             return val
         except KeyError:
-            pytest.skip("no %r value found" %(name,))
+            import pytest
+            py.test.skip("no %r value found" %(name,))
 
 def exists(path, ignore=EnvironmentError):
     try:

_pytest/core.py

@@ -4,7 +4,7 @@ pytest PluginManager, basic initialization and tracing.
 import sys
 import inspect
 import py
-import pytest
+# don't import pytest to avoid circular imports
 
 assert py.__version__.split(".")[:2] >= ['1', '4'], ("installation problem: "
     "%s is too old, remove or upgrade 'py'" % (py.__version__))
@@ -137,7 +137,7 @@ class PluginManager(object):
 
     def skipifmissing(self, name):
         if not self.hasplugin(name):
-            pytest.skip("plugin %r is missing" % name)
+            py.test.skip("plugin %r is missing" % name)
 
     def hasplugin(self, name):
         return bool(self.getplugin(name))
@@ -221,9 +221,9 @@ class PluginManager(object):
             raise
         except:
             e = py.std.sys.exc_info()[1]
-            if not hasattr(pytest, 'skip'):
+            if not hasattr(py.test, 'skip'):
                 raise
-            elif not isinstance(e, pytest.skip.Exception):
+            elif not isinstance(e, py.test.skip.Exception):
                 raise
             self._hints.append("skipped plugin %r: %s" %((modname, e.msg)))
         else: