Small fix in Deferred tasks module.

System version 0.380
modules:
Blogs 0.071
Comments 0.021
Cron 0.008
Deferred tasks 0.0.1+build-2
Disqus 1.0.1+build-2
Feedback 0.006
HybridAuth 2.1.1-cs32
OAuth2 0.031
Photo_gallery 0.016
Plupload 2.0.0-cs2
Static_pages 0.038
plugins:
Admin_default_theme 0.005
Fotorama 4.4.6-cs1
SimpleImage 2.3-cs1
TinyMCE 4.0.10-cs1