TinyMCE multiline and featured image problems

I've been having problems with posts which use Magic Fields multiline. Specifically, the TinyMCE editor did not load for multiline fields and setting the featured image failed. After much digging through the source code, I tracked the problem down to Commit: 5e88e44c8a9ecedb341e01c930f01bda02bae257 [5e88e44] which outputs a TinyMCE editor right at the top of the HTML before even the DocType.