  Let $\mathcal {M}$ be the space of all, including singular, long knots in
3-space and for which a fixed projection into the plane is an immersion. Let
$cl(\Sigma^{(1)}_{iness})$ be the closure of the union of all singular knots in
$\mathcal {M}$ with exactly one ordinary double point and such that the two
resolutions represent the same (non singular) knot type. We call
$\Sigma^{(1)}_{iness}$ the {\em inessential walls} and we call $\mathcal
{M}_{ess} = \mathcal {M} \setminus cl(\Sigma^{(1)}_{iness})$ the {\em essential
diagram space}. We construct a non trivial class in $H^1(\mathcal {M}_{ess};
\mathbb{Z}[A, A^{-1}])$ by an extension of the Kauffman bracket. This implies
in particular that there are loops in $\mathcal {M}_{ess}$ which consist of
regular isotopies of knots together with crossing changings and which are not
contractible in $\mathcal {M}_{ess}$ (leading to the title of the paper).
  We conjecture that our construction gives rise to a new knot polynomial for
knots of unknotting number one.
