[PATCH] ci: work around Debian 12's HTTP/2 authentication failures

["Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>]

From: Johannes Schindelin <johannes.schindelin@gmx.de>

Since 00fa8502354 (ci: bump debian-11 job to debian-12, 2026-09-05), the
`debian-12` job has intermittently failed t5559's half-auth clone with:

  curl 92 Stream error in the HTTP/2 framing layer

Anonymous discovery succeeds, but the upload-pack POST requires
authentication. Apache can return an early 401 and close the HTTP/2
stream before libcurl finishes sending the request body. Debian 12's
curl 7.88.1 treats that closure as a transport error instead of allowing
an authentication retry. Curl fixed this handling in 331b89a319d0
(http2: polish things around POST), included in 8.3.0:
https://github.com/curl/curl/pull/11756

This did not happen before switching to Debian 12 because Debian 11
ships with libcurl 7.74.0-1.3+deb11u16, which does not have that bug.

Replacing the packaged libcurl with a modern build would defeat this
job's purpose of testing older supported distributions. So let's simply
exclude the flaky t5559.15 and its dependent t5559.16 on Debian 12 until
the packaged curl carries the fix (or until the end of time, whichever
comes first).

Assisted-by: GPT-6 Astra
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
    ci: work around Debian 12's HTTP/2 authentication failures
    
    While this is a regression in v2.56, it does not affect production code,
    it's just working around a flaky test. In other words: This patch does
    not need to be fast-tracked into v2.56.0, but it would be good to get it
    into master pretty soon after that, to reduce developer friction.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2236%2Fdscho%2Fwork-around-debian-curl-stream-error-92-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2236/dscho/work-around-debian-curl-stream-error-92-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2236

 ci/lib.sh | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/ci/lib.sh b/ci/lib.sh
index c6ccbf8c17..1cf31b5a2c 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -334,6 +334,12 @@ pull_request,*|push,*next*|push,*master*|push,*main*|push,*maint*)
 esac
 
 case "$distro" in
+debian-12)
+	# Debian 12's curl 7.88.1 mishandles early HTTP/2 responses; see
+	# https://github.com/curl/curl/pull/11756. Skip the half-auth
+	# clone and its dependent fetch until Debian has the fix.
+	export GIT_SKIP_TESTS="$GIT_SKIP_TESTS t5559.15 t5559.16"
+	;;
 ubuntu-*)
 	# Python 2 is end of life, and Ubuntu 23.04 and newer don't actually
 	# have it anymore. We thus only test with Python 2 on older LTS

base-commit: 3bc0341126508f78f5869cbfc0005e987efdf0c7
-- 
gitgitgadget