the regex:

is not able to match the diff generated if this flag is enabled in ~/.gitconfig:

[diff] mnemonicPrefix = true 

because it is expecting [ab]/ as folder prefix for the diff but with mnemonicPrefix enabled it become [wc]/

Diff without mnemonicPrefix

diff --git a/.vscode/launch.json b/.vscode/launch.json index xxxxxxx..xxxxxxxx --- a/.vscode/launch.json+++ b/.vscode/launch.json

Diff with mnemonicPrefix = true

diff --git c/.vscode/launch.json w/.vscode/launch.json index xxxxxxx..xxxxxxxx --- c/.vscode/launch.json+++ w/.vscode/launch.json

Quick Test

repo=git.Repo('.') branch_ref=repo.headancestor_ref=repo.merge_base(branch_ref, repo.refs["main"]) diff=ancestor_ref[0].diff(None, create_patch=True) print(diff)