Make sure the first revision is seen as coming from emptiness, so it can be restored.

props adamsilverstein. fixes #23898.

git-svn-id: https://core.svn.wordpress.org/trunk@23872 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Sanity checks on image metadata to avoid warnings, etc.

fixes #23733. props wonderboymusic.

git-svn-id: https://core.svn.wordpress.org/trunk@23873 1a063a9b-81f0-0310-95a4-ce76da25c4cd