Artin's conjecture in arithmetic progressions

Let $a,b,r\in\mathbb{Z}$ with $\gcd(a,b)=1$, and suppose that $r\neq -1$ and that $r$ is not a perfect $m$th power for any $m>1$. An integer $r$ is a primitive root modulo a prime $q$ when its powers represent all nonzero residue classes modulo $q$. The strengthened Artin conjecture. There exist infinitely many primes $q$ in the arithmetic progression $\{a+kb\}_{k\in\mathbb{Z}}$ such that $r$ is a primitive root modulo $q$. The source presents this as a stronger form of Artin's conjecture, beyond the infinitude assertion without a prescribed progression. It remains open in the source.