fetch saves the manifest as index.mf at the top of the tree and refuses a
manifest that lists a file there. gen given --output, and freshen with its
manifest outside the base directory, listed such a file, so they wrote
manifests fetch would not take.
Both now leave out each file the manifest would list as index.mf: one at
the top of the tree, or a file given to gen by that name. The rule goes by
that path alone and looks up no file, so a symlink named index.mf never
hides the file it points to. index.mf in a subdirectory is still listed.
The scanner in package mfer gets an option to leave out files by the path
they would be listed by.
Model: opus-5-5
sneak