Fix GitHub isDomSplit()
Created by: felixfbecker
Fixes #2957
Adds unit tests for all cases (commit, pr) x (github.com, ghe) x (refined github, vanilla) x (split, unified)
Created by: felixfbecker
Fixes #2957
Adds unit tests for all cases (commit, pr) x (github.com, ghe) x (refined github, vanilla) x (split, unified)