dirstate-v2: fix edge case where entries aren't sorted See previous commit for more details.

dirstate-v2: highlight a bug when Python-packed but used in `rhg` The Python packer creates unsorted entries in the edge case that a file starts with the same name as a sibling folder. This bug has no effect on the Python `hg status` since Python ignores directories. `rhg` assumes that all on-disk entries are sorted (which is a property of the format) including folder, hence the issue highlighted. This is also technically broken in Rust-augmented `hg status`, but it makes setting up the test more complex than necessary, since it requires the packing to be Python only (which it isn't if you have Rust extensions). Fix is in the next commit.

dirstate-v2: correct documented return values of `pack_dirstate`

dirstate-v2: fix typos in docstrings

dirstate-v2: update constant that wasn't kept in sync Despite the best efforts of the comment, this constant wasn't kept in sync when the flags were being rewritten. The fact that this doesn't actually break anything in the Rust implementation too much (which does use directories) relies on the fact that all nodes can have children and that dirstate traversal is not based on that flag, but for metadata in optimizations. However the bug could become more serious should we start encoding stronger guarantees using a combination of flags including this one.

lfs: avoid closing connections when the worker doesn't fork Probably not much more than an minor optimization, but could be useful in the case of `hg verify` where missing blobs are fetched one at a time.