Add env variables to identify workers

xdist/remote.py

@@ -148,6 +148,8 @@ if __name__ == '__channelexec__':
     os.environ['PYTHONPATH'] = (
         importpath + os.pathsep +
         os.environ.get('PYTHONPATH', ''))
+    os.environ['PYTEST_XDIST_WORKER'] = slaveinput['slaveid']
+    os.environ['PYTEST_XDIST_WORKER_COUNT'] = str(slaveinput['slavecount'])
     # os.environ['PYTHONPATH'] = importpath
     import py
     config = remote_initconfig(option_dict, args)

xdist/slavemanage.py

@@ -205,7 +205,8 @@ class SlaveController(object):
         self.putevent = putevent
         self.gateway = gateway
         self.config = config
-        self.slaveinput = {'slaveid': gateway.id}
+        self.slaveinput = {'slaveid': gateway.id,
+                           'slavecount': len(nodemanager.specs)}
         self._down = False
         self._shutdown_sent = False
         self.log = py.log.Producer("slavectl-%s" % gateway.id)