Git: Fix popping of branch-stash after checkout

Checking out a branch that has a saved stash, when
Pop branch stash is checked, is broken since checkout
became asynchronous.

We must wait for checkout to complete before popping
the branch stash.

Change-Id: Ia4d43649e742ced0121ffe106986b4d6ed1e7b38
Reviewed-by: André Hartmann <aha_1980@gmx.de>

src/plugins/git/branchmodel.h

@@ -30,6 +30,8 @@
 #include <QAbstractListModel>
 #include <QVariant>
 
+namespace VcsBase { class VcsCommand; }
+
 namespace Git {
 namespace Internal {
 
@@ -78,7 +80,7 @@ public:
 
     void removeBranch(const QModelIndex &idx);
     void removeTag(const QModelIndex &idx);
-    void checkoutBranch(const QModelIndex &idx);
+    VcsBase::VcsCommand *checkoutBranch(const QModelIndex &idx);
     bool branchIsMerged(const QModelIndex &idx);
     QModelIndex addBranch(const QString &name, bool track, const QModelIndex &trackedBranch);
     void setRemoteTracking(const QModelIndex &trackingIndex);