hg - Ignore directory at root only

As of Mercurial 4.9, you can use syntax: rootglob to insert rooted glob patterns.

New rootglob: filename pattern for a glob that is rooted at the root of the repository. See hg help patterns and hg help hgignore for details

You can include syntax: regexp at the beginning of .hgignore and then use perl regex syntax to root a directory by using ^. So just ^static should do the work.