Memory leak

Separate from the other report, this one's occurring regardless of the fetch, but we need to check the background fetch isn't having an impact on the memory consumption also.

https://answers.atlassian.com/questions/149345/source-tree-1-5-7-1-memory-leaks?sort=votes&page=2

Reaching 6GB on memory usage for a user according to the AAC issue. More details to follow.