Changes

Changes from Mercurial (hg https://isabelle.in.tum.de/repos/isabelle/ default)

Changeset 80137:0c51e0a6bc37 by simon wimmer _wimmers@in.tum.de_: sketch & explore: recover from duplicate fixed variables in Isar proofs
The file was modified	`src/HOL/ex/Sketch_and_Explore.thy`