haproxy: Fix compatibility when map is actually imap. (#3350)

While I still have no idea why or how the `map` call is being swapped out while still running in python 2.7, this change will fix the following error, as well as improve py3 compatibility.

network/haproxy.py

@@ -211,7 +211,7 @@ def discover_all_backends(self):
         """
         data = self.execute('show stat', 200, False).lstrip('# ')
         r = csv.DictReader(data.splitlines())
-        return map(lambda d: d['pxname'], filter(lambda d: d['svname'] == 'BACKEND', r))
+        return tuple(map(lambda d: d['pxname'], filter(lambda d: d['svname'] == 'BACKEND', r)))
 
 
     def execute_for_backends(self, cmd, pxname, svname, wait_for_status = None):
@@ -244,7 +244,7 @@ def get_state_for(self, pxname, svname):
         """
         data = self.execute('show stat', 200, False).lstrip('# ')
         r = csv.DictReader(data.splitlines())
-        state = map(lambda d: { 'status': d['status'], 'weight': d['weight'] }, filter(lambda d: (pxname is None or d['pxname'] == pxname) and d['svname'] == svname, r))
+        state = tuple(map(lambda d: { 'status': d['status'], 'weight': d['weight'] }, filter(lambda d: (pxname is None or d['pxname'] == pxname) and d['svname'] == svname, r)))
         return state or None