Expected behaviour

Importing should skip macOS shadow files in .tar.gz archive.

Actual behaviour

Importing wastes processing time trying to import the file (e.g. "._newemoji.png") as a PNG file, when it isn't one. Also counts it as a failed import at the end, resulting in equal number imported and 'failed'.
Produces error for each emoji:

Failure/Error: emoji/._test_emoji.png
    has contents that are not what they are reported to be, is invalid

Steps to reproduce the problem

Import an emoji .tar.gz file that was made on a mac, or with a folder edited on a mac.

Specifications

Seen in 3.3.0rc3, present since emoji import implemented.