check_output
'
+. "$TEST_DIRECTORY"/lib-httpd.sh
+start_httpd
+
+REPO="$HTTPD_DOCUMENT_ROOT_PATH/repo"
+LOCAL_PRISTINE="$(pwd)/local_pristine"
+
+test_expect_success 'setup repos for change-while-negotiating test' '
+ (
+ git init "$REPO" &&
+ cd "$REPO" &&
+ >.git/git-daemon-export-ok &&
+ test_commit m1 &&
+ git tag -d m1 &&
+
+ # Local repo with many commits (so that negotiation will take
+ # more than 1 request/response pair)
+ git clone "http://127.0.0.1:$LIB_HTTPD_PORT/smart/repo" "$LOCAL_PRISTINE" &&
+ cd "$LOCAL_PRISTINE" &&
+ git checkout -b side &&
+ for i in $(seq 1 33); do test_commit s$i; done &&
+
+ # Add novel commits to upstream
+ git checkout master &&
+ cd "$REPO" &&
+ test_commit m2 &&
+ test_commit m3 &&
+ git tag -d m2 m3
+ ) &&
+ git -C "$LOCAL_PRISTINE" remote set-url origin "http://127.0.0.1:$LIB_HTTPD_PORT/one_time_sed/repo" &&
+ git -C "$LOCAL_PRISTINE" config protocol.version 2
+'
+
+inconsistency () {
+ # Simulate that the server initially reports $2 as the ref
+ # corresponding to $1, and after that, $1 as the ref corresponding to
+ # $1. This corresponds to the real-life situation where the server's
+ # repository appears to change during negotiation, for example, when
+ # different servers in a load-balancing arrangement serve (stateless)
+ # RPCs during a single negotiation.
+ printf "s/%s/%s/" \
+ $(git -C "$REPO" rev-parse $1 | tr -d "\n") \
+ $(git -C "$REPO" rev-parse $2 | tr -d "\n") \
+ >"$HTTPD_ROOT_PATH/one-time-sed"
+}
+
+test_expect_success 'server is initially ahead - no ref in want' '
+ git -C "$REPO" config uploadpack.allowRefInWant false &&
+ rm -rf local &&
+ cp -r "$LOCAL_PRISTINE" local &&
+ inconsistency master 1234567890123456789012345678901234567890 &&
+ test_must_fail git -C local fetch 2>err &&
+ grep "ERR upload-pack: not our ref" err
+'
+
+test_expect_success 'server is initially behind - no ref in want' '
+ git -C "$REPO" config uploadpack.allowRefInWant false &&
+ rm -rf local &&
+ cp -r "$LOCAL_PRISTINE" local &&
+ inconsistency master "master^" &&
+ git -C local fetch &&
+
+ git -C "$REPO" rev-parse --verify "master^" >expected &&
+ git -C local rev-parse --verify refs/remotes/origin/master >actual &&
+ test_cmp expected actual
+'
+
+stop_httpd
+
test_done