Yes, it is hard coded on 4.0.x. In 3.x, you can add a
count=100000 parameter to increase the number of results returned.
Why is it hard coded? Is there an alternative to count sources that's as quick as using the metadata?
It is tunable in 4.1.x in limits.conf.
Add to etc/system/local/limits.conf:
[metadata] maxcount = *some larger number*