Close the config file properly

Author: radomirbosak

jenkins_cli/cli.py

@@ -126,7 +126,8 @@ def read_settings_from_file(cls, environment):
         # read the config file
         config = ConfigParser()
         try:
-            config.readfp(open(filename, 'r'))
+            with open(filename, 'r') as f:
+                config.readfp(f)
         except Exception as e:
             raise CliException('Error reading %s: %s' % (filename, e))