mh-remove-from-sub-folders-cache

mh-remove-from-sub-folders-cache is an autoloaded Lisp function in `mh-utils.el'.

(mh-remove-from-sub-folders-cache FOLDER)

Remove FOLDER and its parent from `mh-sub-folders-cache'.
FOLDER should be unconditionally removed from the cache. Also the
last ancestor of FOLDER present in the cache must be removed as
well.

To see why this is needed assume we have a folder +foo which has
a single sub-folder qux. Now we create the folder +foo/bar/baz.
Here we will need to invalidate the cached sub-folders of +foo,
otherwise completion on +foo won't tell us about the option
+foo/bar!