It seems that Metalsmith is trying to stat everything in source dir before applying .ignore. That is inconvenient when using Emacs, for example, which creates such symlinks for its own agenda. It also seems that applying .ignore before .source makes no difference.

Error that fails the build

Error: ENOENT: no such file or directory, stat '/path/to/broken/symlink/in/source/dir'

Steps to reproduce

1. Create broken symbolic link anywhere in source dir
2. Add link name or matching pattern to .ignore
3. Build with .build