eol: explain why reading .hgeol from the working dir is special

hgext/eol.py

@@ -191,6 +191,8 b' def reposetup(ui, repo):'
             if data is None:
                 try:
                     if node is None:
+                        # Cannot use workingctx.data() since it would load
+                        # and cache the filters before we configure them.
                         data = self.wfile('.hgeol').read()
                     else:
                         data = self[node]['.hgeol'].data()