revert: detect unknown files in the same path as files marked as removed Such unknown files may need to be backed up. Having them identified beforehand will help simplify the backup logic. We now use different sets with different backup strategies.

revert: cache working context in a variable During the silicon age, humans on planet Earth discovered the use of variables. This marvelous invention let them improve both code readability and performance.

obsolete: properly drop 'date' from metadata Mistakes were made while resolving rebase conflicts in 4bc96685a40c. This led to 'date' being preserved in metadata when reading markers from a binary stream. As a result, some known markers were seen as "new" when pulling. I noticed it because a no-op pulls from main added about 600 duplicated markers to my obsstore (for each pull). I do not believe we need to perform any specific action to actively de-duplicates existing obsstore. After this fix, duplicated markers will no be propagated and the few affected repositories can probably deal with duplication (or people can repull the obsstore from a clone). As a side effect, we decode metadata only once, reducing the impact of the hack in fm0 to store extra important data (parents and date).