Enable "View: Reopen editor with..." for diffs

[firelizzard18]

For markdown files I set the default editor to markdown preview. This causes a problem: when I open a git diff (as in by clicking on README.md or whatever in the SCM view) it opens with the markdown preview and doesn't show me any diff.

Thus: I want "View: Reopen editor with..." to work for diffs. With (non-diff) markdown files I can simply double click on the preview to open the text version, but if I do that in a diff it opens the file and not the diff.