Merge branch 'cb/clear-quarantine-early-on-all-ref-update-errors'

"receive-pack" checks if it will do any ref updates (various conditions could reject a push) before received objects are taken out of the temporary directory used for quarantine purposes, so that a push that is known-to-fail will not leave crufts that a future "gc" needs to clean up. * cb/clear-quarantine-early-on-all-ref-update-errors: receive-pack: purge temporary data if no command is ready to run