facebook/react — pull request #1351 by zpao (2014-04-03 23:47:47+00:00)
Title: Warn better for key issues

We weren't warning for key issues at the top level (renderComponent) level at
all. This makes us do that, even if it's not quite perfect.

@sebmarkbage complained to me after it went in that #1334 wasn't really the right fix (true, but it was needed).