Comment 9 for bug 600092

So yes I did
M-x emacs-Q-nxhtml
and in the new emacs simply

C-x C-f test.mak
M-x mako-html-mumamo-mode
And then I started to type something, when I arrived at the second line:

<%def func="name">
<%/

It started to go crazy and it becomes unusable (also selection doesn't work) until I change mode.

But the error is always the same as seen above.
And the same thing happens if I paste a perfectly correct mako file inside my buffer after passing to mako-html-mumamo-mode