This is a ticket for multiple proposed extensions to mongodump --repair:

• Currently, it traverses the list of extents front to back and then back to front. Within each extent, the same back and forth iteration should happen for the records for the case in which the intra-extent record chain is broken.

• De-duplication should be done across the two stages, otherwise we are returning possibly 2x the number of records.

• Possibly search for the magic extent number to find unreachable extents.