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.

mercurial/dirstateutils/v2.py

@@ -56,7 +56,7 b' assert TREE_METADATA_SIZE == TREE_METADA'
 assert NODE_SIZE == NODE.size
 
 # match constant in mercurial/pure/parsers.py
-DIRSTATE_V2_DIRECTORY = 1 << 5
+DIRSTATE_V2_DIRECTORY = 1 << 13
 
 
 def parse_dirstate(map, copy_map, data, tree_metadata):