Patch by Zachary Ware

Initial patch by Alon Horev

#15114: The html.parser module now raises a DeprecationWarning when the strict argument of HTMLParser or the HTMLParser.error method are used.

Issue #19286: Adding test demonstrating the failure when a directory is found in the package_data globs.

importlib.machinery.FileFinder.

While originally moved to stop special-casing '' as PathFinder farther
up the typical call chain now uses the cwd in the instance of '', it
was deemed an unnecessary risk to breaking subclasses of FileFinder to
take the special-casing out.