UPD: I did setup just like yours is and can repro the very same error in the console 100%. Just like in your configuration, I created
vendor/dir2 (symlink to dir1):
I dig further thru the codebase of
listen gems and here is what I have found. The reason why the error message appears is because one of the
listen gem components, record.rb, in _fast_build_dir method, indexing all the children items without taking into account the exclusion list and therefore prints out the error message.
Good news however, locations configured in
_config.yml actually are excluded from the list of those being watched despite of the error. So, it is not a critical error per se - your Jekyll instance should remain fully functional.
The error message however a bit annoying and very confusing. I guess I have a clue how to fix it in the original code base...