Artur Malabarba wrote:
> The actual binding was supposed to be C-x C-;. The problem with bootstrap
> surprises me, but I guess it must be something in the order that files are
> loaded.

It's because if you try to evaluate the string "\C-;", Emacs throws (error 
"Invalid modifier in string").  I installed the attached patch to use the 
keybinding that you wanted.  This should fix the bug, so I'm closing the bug report.