Version photos when updating EXIF

[jmathai]

Since updating EXIF rewrites the file and can cause corruption we should consider copying the previous version of the file to some known location.

Taken from this comment on Medium.
https://medium.com/@sacherjj/with-exif-you-are-rewriting-the-file-every-time-you-change-anything-6aa25c5835fa#.4wjcrzpcg

[bdillahu]

Just as an idea, maybe just dump out the EXIF each time it changes and version that... it wouldn't save from file corruption (that's for backups and bitrot detection), but it would save from the accidental trashing of EXIF data (input wrong date, etc.)

[jmathai]

@bdillahu dumping the EXIF is an interesting idea. If we version the photos themselves it also backs up the EXIF (inside the backed up photo). It's a bit heavy handed but in the point taken from the comment on Medium it serves the primary purpose of protecting all the bits of a photo when it's modified and not just EXIF.

Dumping the EXIF is more closely related to supporting XMP sidecar files. I thought there was an issue for it but can't seem to find one.

[chrisweis]

#341