Hi,

On Thu, 27 Aug 2020, Jiang Xin wrote:

> +test_expect_success "setup proc-receive hook (hook --die-readline, $PROTOCOL)" '
> +	write_script "$upstream/hooks/proc-receive" <<-EOF
> +	printf >&2 "# proc-receive hook\n"
> +	test-tool proc-receive -v --die-readline
> +	EOF
> +'
> +
> +# Refs of upstream : master(A)
> +# Refs of workbench: master(A)  tags/v123
> +# git push         :                       refs/for/master/topic(A)
> +test_expect_success "proc-receive: bad protocol (hook --die-readline, $PROTOCOL)" '
> +	test_must_fail git -C workbench push origin \
> +		HEAD:refs/for/master/topic \
> +		>out 2>&1 &&
> +	make_user_friendly_and_stable_output <out >actual &&
> +
> +	grep "remote: fatal: protocol error: expected \"old new ref\", got \"<ZERO-OID> <COMMIT-A> refs/for/master/topic\"" actual &&
> +
> +	git -C "$upstream" show-ref >out &&
> +	make_user_friendly_and_stable_output <out >actual &&
> +	cat >expect <<-EOF &&
> +	<COMMIT-A> refs/heads/master
> +	EOF
> +	test_cmp expect actual
> +'

While investigating a flaky hang in t5411 in the osx-clang job of our
CI/PR builds, I ran into this issue (with --stress):

-- snip --
[...]
+++ test_must_fail git -C workbench push origin HEAD:refs/for/main/topic
+++ case "$1" in
+++ _test_ok=
+++ test_must_fail_acceptable git -C workbench push origin HEAD:refs/for/main/topic
+++ test git = env
+++ case "$1" in
+++ return 0
+++ git -C workbench push origin HEAD:refs/for/main/topic
+++ exit_code=128
+++ test 128 -eq 0
+++ test_match_signal 13 128
+++ test 128 = 141
+++ test 128 = 269
+++ return 1
+++ test 128 -gt 129
+++ test 128 -eq 127
+++ test 128 -eq 126
+++ return 0
+++ make_user_friendly_and_stable_output
++++ echo 4844d8acf2fc62b151a29cfb3b916b6778476b9e
++++ cut -c1-7
++++ echo c208c3bb8a1aeea6d4e40027a17251ccd59a2b1b
++++ cut -c1-7
+++ sed -e 's/  *$//' -e 's/   */ /g' -e 's/'\''/"/g' -e 's/    /    /g' -e 's/4844d8acf2fc62b151a29cfb3b916b6778476b9e/<COMMIT-A>/g' -e 's/c208c3bb8a1aeea6d4e40027a17251ccd59a2b1b/<COMMIT-B>/g' -e 's/f7cc02ec1b3393b9a9638a0e02a7039c234cffa4/<TAG-v123>/g' -e 's/0000000000000000000000000000000000000000/<ZERO-OID>/g' -e 's/4844d8a[0-9a-f]*/<OID-A>/g' -e 's/c208c3b[0-9a-f]*/<OID-B>/g' -e 's#To \.\./upstream.git#To <URL/of/upstream.git>#' -e '/^error: / d'
+++ grep 'remote: fatal: protocol error: expected "old new ref", got "<ZERO-OID> <COMMIT-A> refs/for/main/topic"' actual
error: last command exited with $?=1
not ok 34 - proc-receive: bad protocol (hook --die-readline, builtin protocol)
#
#               test_must_fail git -C workbench push origin \
#                       HEAD:refs/for/main/topic \
#                       >out 2>&1 &&
#               make_user_friendly_and_stable_output <out >actual &&
#
#               grep "remote: fatal: protocol error: expected \"old new
#               ref\", got \"<ZERO-OID> <COMMIT-A> refs/for/main/topic\""
#               actual &&
#
#               git -C "$upstream" show-ref >out &&
#               make_user_friendly_and_stable_output <out >actual &&
#               cat >expect <<-EOF &&
#               <COMMIT-A> refs/heads/main
#               EOF
#               test_cmp expect actual
#
-- snap --

The output of `actual` reads like this:

-- snip --
remote: # pre-receive hook
remote: pre-receive< <ZERO-OID> <COMMIT-A> refs/for/main/topic
remote: # proc-receive hook
fatal: unable to write flush packet: Broken pipe
send-pack: unexpected disconnect while reading sideband packet
fatal: the remote end hung up unexpectedly
-- snap --

Applying Gábor's patch as obtained from
https://lore.kernel.org/git/20190830121005.GI8571@szeder.dev/ seemed to
help this issue at first, but then turned out not to prevent the same
issue from happening again.

Any ideas?

Ciao,
Johannes