Remove the branch from the listing after the instance is removed

managetests/app.py

@@ -174,6 +174,7 @@ class TestsManager:
 
             self.instances.remove_branch(branch)
             self.branches[branch].destroy()
+            del self.branches[branch]
 
         # The instance should be created
         elif branch not in self.branches and obj["state"] == "opened":