proper support for "isabelle update -D DIR": avoid accidental exclusion of select_dirs (amending e5dafe9e120f);
#built-in components
src/Tools/Demo
src/Tools/jEdit
src/Tools/GraphBrowser
src/Tools/Graphview
src/Tools/Setup
src/Tools/VSCode
src/HOL/Mutabelle
src/HOL/Library/Sum_of_Squares
src/HOL/SPARK
src/HOL/Tools
src/HOL/TPTP