The error message:
`editor.file_changed_while_editing = The file contents have changed
since you started editing. <a target="_blank" rel="noopener noreferrer"
href="%s">Click here</a> to see them or <strong>Commit Changes
again</strong> to overwrite them.`
Is re-used in inappropriate contexts. The link in the key goes to a 404
when the key is used in a situation where the file contents have not
changed.
Added two new keys to differentiate commit id mismatch and push out of
date conditions.