block metadata changes on shared images
block metadata changes on shared images

If images are shared (ref count > 1), block changes to the set of
metadata items on the image. These can cause crashes in highly threaded
programs.

See https://github.com/lovell/sharp/issues/1986

jcupitt/libvips,lovell/libvips,jcupitt/libvips,jcupitt/libvips,lovell/libvips,jcupitt/libvips,lovell/libvips,lovell/libvips