Previously, proxied and local images were checked for presence in the
storage before previewing or posting the comment. That logic resulted in
an inability to post with an image when a proxy for images is enabled,
as proxied images are not downloaded to disk before the first time
someone loads them, which could only happen after the user either
previews or posts the message.
After this change, preview and post only checks the local images'
presence and ignore the proxied ones.
Dmitry VerkhoturovandUmputun
c72f30eabb