rebber-plugins: \{ and \} improperly eaten

[artragis]

When we sanitize the commands we remove the backslash :

Input

$$\boxed{\nabla^2 E(\vec x) + \left\{[n(\vec{x})\,k]^2-i\,k\,\sigma(\vec x)\right\}\,E(\vec x) = -s(\vec x)},$$

Current output

$$\boxed{  E(\vec x) + \left {[n(\vec{x}) ]^2-i \,\sigma(\vec x)\right } (\vec x) = -s(\vec x)},$$

Expected output

$$\boxed{\nabla^2 E(\vec x) + \left\{[n(\vec{x})\,k]^2-i\,k\,\sigma(\vec x)\right\}\,E(\vec x) = -s(\vec x)},$$