Use next(iterator) rather than iterator.next()

iterator.next() was replaced with iterator.__next__() in Python 3.
Use next(iterator) instead which will select the correct method for
returning the next item.

Change-Id: I6d0c89c8b32e817e5897fe87332933dacf22027b

subcmds/status.py

@@ -113,7 +113,7 @@ the following meanings:
     try:
       state = project.PrintWorkTreeStatus(output)
       if state == 'CLEAN':
-        clean_counter.next()
+        next(clean_counter)
     finally:
       sem.release()
 
@@ -141,7 +141,7 @@ the following meanings:
       for project in all_projects:
         state = project.PrintWorkTreeStatus()
         if state == 'CLEAN':
-          counter.next()
+          next(counter)
     else:
       sem = _threading.Semaphore(opt.jobs)
       threads_and_output = []
@@ -164,7 +164,7 @@ the following meanings:
         t.join()
         output.dump(sys.stdout)
         output.close()
-    if len(all_projects) == counter.next():
+    if len(all_projects) == next(counter):
       print('nothing to commit (working directory clean)')
 
     if opt.orphans: