Inaccessible mount point causes parent directory to be skipped

[geoffreybennett]

When backing up /home as root, I have found that:

• if a user has an sshfs mount within their home directory (which is by default inaccessible to root), then kopia skips the entirety of the containing directory (i.e. the user's home directory) and I get the message "Ignored 1 error(s) while snapshotting root@hostname:/home"
• if there is an sshfs mount within /home (e.g. at /home/anyuser), then nothing gets backed up (no snapshot) and there's a misleading error message: "upload error: permission denied"

It was not possible to fix this error and get a complete backup by setting "Scan one filesystem only", "Ignore file/directory read errors", or by putting the problematic directories into .kopiaignore, because the attempted stat on the sshfs directory causes its parent directory scan to be aborted before the filesystem/error/ignore checks are done.

I will submit a PR which fixes these issues shortly.