The section in the developer guide about Merging still discourages devs from using the "big green button" on github. That's out of date now: it's probably better to use it, because you'll be sure that you're rebased against master and travis completed. I don't know that we have any repositories for which it's not safe to use: if so, we could either document them, or list the conditions under which we shouldn't use it.

Please update that paragraph to reflect this.