The problem is a bit more complex.
First of all, it only affects commercial shipyards, so a simple doubling of the racial build speed won't be a balanced fix.
More importantly, though, is that it doesn't simply halve the expected ABR. Instead, the bug involves the game taking the size of every commercial vessel to be 0 tons when determining the effective build rate. With the way the effective build rate is calculated, this results in an effective build rate that will always be at half your racial. It doesn't matter if you're building a 1000ton or a 100,000ton vessel.