alphagov/whitehall — comment on commit 25cd2f7e0713ecc40a7f9f2140b1e8a463d76a6c
File:  line 0
By craigw:

Depends on the browser but from what I remember playing with this stuff about 2 years ago, if the response is a 2XX and includes `Last-Modified` or `ETag` headers then there's a conditional get no matter what other headers you set to whatever value.

Would love to know if I've remembered that correctly - did you find similar behaviour?