Merge branch 'tb/midx-write-corrupt-checksum-fix'

The logic that avoids reusing MIDX files with a wrong checksum was broken, which has been corrected. * tb/midx-write-corrupt-checksum-fix: midx-write.c: assume checksum-invalid MIDXs require an update t/t5319-multi-pack-index.sh: drop early 'test_done'