Git: Update current branch after some operations

... to refresh the branch view upstream status.

No need for a full model update here, only the current
branch is influenced.

Change-Id: I6bd17a841988b36221e5015a5858071d33a7b5e5
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/branchmodel.h

@@ -86,6 +86,7 @@ public:
     void setRemoteTracking(const QModelIndex &trackingIndex);
     void setOldBranchesIncluded(bool value);
     Utils::optional<QString> remoteName(const QModelIndex &idx) const;
+    void refreshCurrentBranch();
 
 private:
     void setCurrentBranch();