Issue Type: Bug

Now that clicking a secondary action causes the items in the tree to be selected, I am seeing double selection in the tree as the previous selection is not cleared. This seems to only occur with git.openDiffOnClick as false

Extension version: 0.9.0
VS Code version: Code - Insiders 1.37.0-insider (46cc0a1670b7047e610aaef1bf84f1190802e9ec, 2019-07-11T05:39:08.167Z)
OS version: Linux x64 5.1.15-surface-linux-surface snap