Upgrade to SourceTree 1.8.2 breaks git filter support

See attached video for a walk-through of the bug, but here's a text description:

We have a smudge/clean filter called "git bin" (https://github.com/seeq12/git-bin) that we use to deal with large files. (git-lfs didn't exist until recently or we probably would have used that.)

As of my upgrade this morning to SourceTree 1.8.2, SourceTree's invocation of git no longer finds the "git bin" filter. Invoking "git bin" works fine from the Windows command line and from Git Bash.

This is being encountered with other developers on our team as well.

I tried to debug it a little bit-- using Process Explorer I confirmed that both SourceTree.exe and any spawned Git.exe processes have the correct Path environment variable. So I don't know what could be going wrong.