One of the things that has been hindering PowerBuilder users from adopting Git for source control has been the lack of a MSSCCI provider for Git. That changed when PB Software released their provider in 2014, although I didn't discover it until 2017 and wrote about it in this blog post.
Of course, one of the new features in PowerBuilder 2017 R2 is native support for Git, so if you're using that version then the lack of a MSSCCI provider for Git is no longer an issue. However, if you're on an older version of PowerBuilder, you still need such provider.
The good news is that since I wrote that original article another MSSCCI provider for Git has become available. In September of 2017, the folks who make the Zeus editor and the AgentSVN MSSCCI provider for SVN announced the release of AgentGit, a MSSCCI provider for Git.
I haven't tried this new Git provider yet, but I do use their SCN provider and it's quite solid. I would expect their Git provider to work equally as well. They also have a try before you buy option so you can check it out for yourself for free.