Merge branch 'jt/upload-pack-error-report' into maint

"git upload-pack", which is a counter-part of "git fetch", did not report a request for a ref that was not advertised as invalid. This is generally not a problem (because "git fetch" will stop before making such a request), but is the right thing to do. * jt/upload-pack-error-report: upload-pack: report "not our ref" to client