Fixed second-thread importing of select module. Also slight patcher fix.

eventlet/hubs/__init__.py

@@ -1,3 +1,4 @@
+import select
 import sys
 import threading
 _threadlocal = threading.local()
@@ -29,7 +30,6 @@ def get_default_hub():
         import eventlet.hubs.epolls
         return eventlet.hubs.epolls
     except ImportError:
-        import select
         if hasattr(select, 'poll'):
             import eventlet.hubs.poll
             return eventlet.hubs.poll

eventlet/patcher.py

@@ -60,5 +60,7 @@ def patch_function(func, *additional_modules):
             for name, mod in additional_modules:
                 if saved[name] is not None:
                     sys.modules[name] = saved[name]
+                else:
+                    del sys.modules[name]
     return patched