Decide if we should do something about previewing issue updates in D7

In D6, when you preview a comment on an issue node, you see a table of any issue metadata updates. This is really helpful to help catch x-posting problems, and to just ensure you're really updating what you meant to update.

In D7, when you edit an issue, if you preview, you only see the new issue, but you get no indication of what changed.

Maybe the solution here is to recommend sites install diff.module? Then, at least you get a "View changes" button that tries to show you the diff of your edit. Sadly, that doesn't yet help much, due to this bug: #1550698: Diff of "select from list" fields shows change in key, not change in value. But, at least it's an existing contrib (already enabled on d.o) that basically solves this problem without us having to do any custom code.

Before anyone writes any code, let's decide what we want to do here. Perhaps all we need is to add this to project_issue.info:

recommends[] = diff

And put some text about it on the project node and the README/INSTALL file(s).

Related Issues

#1545952: [META] UI for updating an issue in D7

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