Ivanov's conjecture on finite-index subgroups of mapping class groups

Let $S_g^n$ be a compact oriented surface of genus $g$ with $n$ boundary components, and let $\mathrm{Mod}(S_g^n)$ be its mapping class group. Let $\Gamma\subset\mathrm{Mod}(S_g^n)$ be a finite-index subgroup, and write $\Gamma^{\mathrm{ab}}$ for its abelianization and $H^1(\Gamma,\mathbb{Z})$ for its first integral cohomology. Ivanov's conjecture. For $g\geq 3$ and $n\geq 0$, $\Gamma^{\mathrm{ab}}=H^1(\Gamma,\mathbb{Z})$ is finite. This is a central finite-abelianization conjecture for finite-index subgroups of mapping class groups. The paper notes substantial partial results and the relation to the Putman–Wieland conjecture, but does not state a resolution in the supplied text.