Gallery blank image issue

[httpdispatch]

Sometimes even if image is downloaded successfully it may not appear in the gallery showing blank black square. It may be related to image worker cancelPotentialWork logic.

Another case is if application was suspended or opened another activity, but this is by design. Need to locate and fix first case

[httpdispatch]

second case may be caused by multithread loading for same file path. Need to handle this behaviours more accurate