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).

templater: implement __len__ for _hybrid Objects of class _hybrid are returned by such template keywords as children, bookmarks, tags and others, and also by revset() template function. They are representing "list of strings" (as hg help template says) for use in templates. So it would be logical to implement a handy way to count the number of strings in such list, and that's what __len__ method does.