dirstate-tree: Remove newly-empty nodes after removing a `DirstateEntry`
This is actually necessary to make `DirstateMap::has_dir` correct, since it
assumes that a node without a `DirstateEntry` has at least one descedant node
with a `DirstateEntry`.
This bug would become apparent when a later changeset persists tree nodes
on disk in the "dirstate-v2" format.
Differential Revision: https://phab.mercurial-scm.org/D10706
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}