Do not change PYTHONPATH or sys.path on local workers

Fix pytest-dev#376

Author: nicoddemus

changelog/376.feature.rst

@@ -0,0 +1,3 @@
+The current directory is no longer added ``sys.path`` for local workers, only for remote connections.
+
+This behavior is surprising because it makes xdist runs and non-xdist runs to potentially behave differently.

xdist/remote.py

@@ -251,17 +251,20 @@ def remote_initconfig(option_dict, args):
 
 
 if __name__ == "__channelexec__":
+    import py
+
     channel = channel  # noqa
-    workerinput, args, option_dict = channel.receive()
-    importpath = os.getcwd()
-    sys.path.insert(0, importpath)  # XXX only for remote situations
-    os.environ["PYTHONPATH"] = (
-        importpath + os.pathsep + os.environ.get("PYTHONPATH", "")
-    )
+    workerinput, args, option_dict, change_sys_path = channel.receive()
+
+    if change_sys_path:
+        importpath = os.getcwd()
+        sys.path.insert(0, importpath)
+        os.environ["PYTHONPATH"] = (
+            importpath + os.pathsep + os.environ.get("PYTHONPATH", "")
+        )
+
     os.environ["PYTEST_XDIST_WORKER"] = workerinput["workerid"]
     os.environ["PYTEST_XDIST_WORKER_COUNT"] = str(workerinput["workercount"])
-    # os.environ['PYTHONPATH'] = importpath
-    import py
 
     config = remote_initconfig(option_dict, args)
     config._parser.prog = os.path.basename(workerinput["mainargv"][0])

xdist/workermanage.py

@@ -245,7 +245,9 @@ def setup(self):
                 option_dict["basetemp"] = str(basetemp.join(name))
         self.config.hook.pytest_configure_node(node=self)
         self.channel = self.gateway.remote_exec(xdist.remote)
-        self.channel.send((self.workerinput, args, option_dict))
+        # change sys.path only for remote workers
+        change_sys_path = not self.gateway.spec.popen
+        self.channel.send((self.workerinput, args, option_dict, change_sys_path))
         if self.putevent:
             self.channel.setcallback(self.process_from_remote, endmarker=self.ENDMARK)