[6.9.2] Mover does not move symlink files targeting non-existent files

Problem description

Under Unraid 6.9.2, mover appears to leave symbolic link files targeting non-existent files ("broken" symlink files) in the cache forever.

Though such symlinks are commonly called "broken" or "invalid" symlinks, those titles are a bit misleading; in truth, though they "feel" weird, they are perfectly legitimate file system objects with a variety of purposes and reasons for existing, so I hope/assume this is simply a bug and/or oversight in mover.

How to reproduce

Simply make a symlink to an invalid path in a user share that uses the cache, like this...

# ln -s /foo/bar /mnt/user/test/symlink

...then start the mover, and check to see if the symlink file has been moved to the array.

Notes

1. I see this both on a mature production server and on a newer box that still has a close-to-vanilla configuration; the attached diagnostics are from the latter.
2. Before capturing diagnostics, I turned mover logging on and started mover to test against a /mnt/user/test/test_symlink file.
3. I see "/mnt/cache/test/test_symlink No such file or directory" appears in the syslog, which may be a clue as to the bug causing this: broken symlink files are peculiar in that some methods of testing for existence fail because the symlink's target file doesn't exist (because the symlink is being "followed"). Here's an example of what I mean, in hopes it helps:

root@Tower:/mnt/user/test# ls -la test_symlink
lrwxrwxrwx 1 root root 18 Apr 28 08:21 test_symlink -> /invalid/test/path
root@Tower:/mnt/user/test# [[ -e test_symlink ]] && echo "exists" || echo "does not exist"
does not exist
root@Tower:/mnt/user/test# [[ -L test_symlink ]] && echo "exists" || echo "does not exist"
exists

protekto-diagnostics-20210428-1027.zip