RtD build successful but it doesn't look very successful to me? https://rasterio--3340.org.readthedocs.build/en/3340/api/rasterio.merge.html

Tons of error messages being ignored in CI: https://app.readthedocs.org/projects/rasterio/builds/28225487/

@adamjstewart we (mostly me) haven't been able to keep up with recent GDAL releases, which change warp output and also trigger a warning that we don't handle (it's turned into an error). If this PR doesn't change code execution, I might merge it regardless.

I still want to double check if the docs are now formatting correctly, let me at least fix the docs before merging.

I probably can't help too much with GDAL churn, but I can help keep the docs building cleanly. I'll see if I can fix enough warnings/errors that we can enable "fail-on-warning" for the docs build.

Okay, can confirm that the docs look good now, added a screenshot above. Should be ready to merge.