[MRG+1] Fix safe_indexing with read-only indices#9507

ogrisel merged 1 commit intoscikit-learn:masterscikit-learn/scikit-learn:masterfrom

lesteve:fix-safe-indexing-with-read-only-indiceslesteve/scikit-learn:fix-safe-indexing-with-read-only-indicesCopy head branch name to clipboard