When adding a new repository tab (New tab > Add), I am prompted to set a custom name for easy reference, which will become the tab's name.

Upon exiting and re-entering Sourcetree the tab names are lost and reverted to the root folder's name. This is a bit of a nuissance since in my case all my projects' root folders are called 'htdocs', causing confusion on which tab is which project, with the risk of operating on the wrong project or forcing me to close all tab add the one I need back.