[modules/dnf] DNF module was not updating properly

Due to name-clashing of the datetime module's "time" alias, time.sleep
didn't work (as it was looked up from the i3bumblebee module),
consequently, the DNF poll thread exited.

While at it, "beautify" the thread cancelling a bit by waiting until
the main thread is not running anymore.

bumblebee/modules/dnf.py

@@ -1,3 +1,5 @@
+from __future__ import absolute_import
+
 import time
 import shlex
 import threading
@@ -16,12 +18,26 @@ def description():
     return "Checks DNF for updated packages and displays the number of <security>/<bugfixes>/<enhancements>/<other> pending updates."
 
 def get_dnf_info(obj):
-    while True:
+
+    loops = 0
+
+    for thread in threading.enumerate():
+        if thread.name == "MainThread":
+            main = thread
+
+    while main.is_alive():
         try:
             res = subprocess.check_output(shlex.split("dnf updateinfo"))
         except Exception as e:
             break
 
+        loops += 1
+        time.sleep(1)
+        if loops < obj.interval():
+            continue
+
+        loops = 0
+
         security = 0
         bugfixes = 0
         enhancements = 0
@@ -47,13 +63,11 @@ def get_dnf_info(obj):
         obj.set("enhancements", enhancements)
         obj.set("other", other)
 
-        time.sleep(obj.interval())
-    
-
 class Module(bumblebee.module.Module):
     def __init__(self, output, args):
         super(Module, self).__init__(args)
-        self._interval = args[0] if args else 30*60
+
+        self._interval = int(args[0]) if args else 30*60
         self._counter = {}
         self._thread = threading.Thread(target=get_dnf_info, args=(self,))
         self._thread.start()