don't fill (break) a specific line in an equation (using % at the end?)

[Uwe Brauer]

Hi all

I usually have auto-fill on and use its filling properties for long
lines in equations by just jumping to the end of that line an typing
space.

However there are some equations for which I do not want to break a
line not even accidently.

So I thought putting a % at the very end of the line (without a space)
would do the thing, but it does not.

Here is an example 

--8<---------------cut here---------------start------------->8---
\begin{equation}
  \label{eq:nordstroem-field:38}
  \left\Vert F(u) \right\Vert_{H^{m}}=\left\Vert G(u)+1 \right\Vert_{H^{m}}\leq 
\left\Vert G(u) \right\Vert_{H^{m}}+1\leq C \left( \left\Vert u 
\right\Vert_{L^{\infty}} \right)+1% 
  \leq C \left( \left\Vert u \right\Vert_{L^{\infty}} \right)\left( 
1+\left\Vert u \right\Vert_{H^{m}} \right)
\end{equation}
--8<---------------cut here---------------end--------------->8---

So under no circumstance should emacs break the line after +1%

But it does. I thought this feature was implemented a long time ago.
What do I miss?

Regards

Uwe Brauer 
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