Use a patch from upstream

The fix you want is already in the package’s own repository. It is just not released yet. You can use that commit as your patch.

The problem: other paths

In the upstream repository, files are often in a sub folder:

src/idna/core.py

In the venv, the package folder is idna/. So the patch must say just core.py. The paths do not fit.

Get the patch

On GitHub, add .patch to the commit URL:

curl -L https://github.com/kjd/idna/commit/<sha>.patch -o patches/idna/0001-fix.patch

Or from a clone:

git format-patch -1 <sha> -o patches/idna

Strip the front of the paths

git am and git apply have -p<n>. It removes n parts from the front of each path. Normally n is 1, which removes a/ and b/.

Path in the patch	Option	Path used
`a/core.py`	`-p1` (default)	`core.py`
`a/idna/core.py`	`-p2`	`core.py`
`a/src/idna/core.py`	`-p3`	`core.py`

So for src/idna/core.py:

version: 1
patches:
  - package: idna
    path: patches/idna/0001-fix.patch
    apply-command: git am -p3

Leave out other files

An upstream commit often also changes tests or docs. Those files are not in the venv, so the patch fails. -p3 also fails on a short path like tests/test_core.py.

So make the patch from the package files only. Add the folder at the end of git format-patch:

git format-patch -1 <sha> -o patches/idna -- src/idna

Now the patch only has files under src/idna/, and git am -p3 works.

Check that it fits

The fix was made against the newest upstream code. Your venv may have an older release. If apply fails, the patch does not fit your version. Then make your own patch. See Write a patch.