Fix broken parser for git diffs with binaries
Review Request #11100 — Created July 28, 2020 and updated
The parser for git diffs (git and hg) did a mistake if there are base64
binary data. It prepended the data to a following file info instead of
appending the previous one.
Cherry-pick of 4e507d418c3420cf49667340f44f82347e845313
Replaced io.BytesIO by StringIO()
Looks like a good fix. I'm going to spend some time going through this and running some internal tests, but we should be able to get this into 3.0.19.