Varnish has normalization logic for URLs, which avoids fragmenting the cache on slightly different percent encodings. While mostly standards-conform, this normalization pass also decodes slashes by default, in line with MediaWiki's policy of allowing literal slashes in titles.
For anything but /wiki/{title}, we would like to only apply standards-compliant normalizations, without decoding slashes.
Options for doing this would be:
- Modify the normalization logic in VCL to (optionally) leave encoded slashes alone, and apply the conservative version to anything but /wiki/.
- Split slash decoding from the general normalization logic, and only apply it for /wiki/.