tests: do not test overwrite without overwrite flag
blob: more sane error code
mobjects: fail startup on critical eblob_get_base_ctl() failure
defrag: honor defrag thresholds
defrag: eblob_want_defrag() failure is acceptable
data-sort: remove old base after unlock

On filesystems like ext3/ext4 file removal can take veeeeery long time
to complete
defrag: added debug