HEAD requests fail with: HTTP/2 stream 1 was not closed cleanly: PROTOCOL_ERROR

[jeroen]

Users of the R bindings found that after a recent libcurl update, the following started failing:

curl --compressed -IL "http://www.dropbox.com/s/srkb2ife75px2yz/modeling_results_BayesSpace_k09.Rdata?dl=1"
# HTTP/2 stream 1 was not closed cleanly: PROTOCOL_ERROR (

If we disable HTTP/2 the request also errors but with chunk hex-length char not a hex digit: 0x1f error:

curl --compressed  -IL --http1.1 "http://www.dropbox.com/s/srkb2ife75px2yz/modeling_results_BayesSpace_k09.Rdata?dl=1"
# chunk hex-length char not a hex digit: 0x1f

curl/libcurl version

I confirmed the problem started appearing on curl 8.6.0 and 8.7.1 on MacOS.

I also confirmed the problem did not appear on curl 8.4.0 on MacOS.

operating system

MacOS

[jeroen]

FYI it is not just http/2 it also happens with http 1.1.

[icing]

The server sends a response to the HEAD request which includes bytes after the headers. This is invalid HTTP (in 1.1 and 2). curl 8.4 ignored these bytes with a warning while 8.6 and newer fail.

I made #13732 to fix this.