Git: Filter obsolete branch names when adding a branch

Task-number: QTCREATORBUG-16264
Change-Id: Ifcb04c7740ab274be590f53757e013da43ad96f1
Reviewed-by: André Hartmann <aha_1980@gmx.de>

src/plugins/git/branchmodel.h

@@ -95,6 +95,7 @@ private:
     BranchNode *m_rootNode;
     BranchNode *m_currentBranch = nullptr;
     QString m_currentSha;
+    QStringList m_obsoleteLocalBranches;
     bool m_oldBranchesIncluded = false;
 };