I have this so far, but I need a hand with the test case.
With a manual hack of the code:
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -2450,7 +2450,7 @@ static int run_update_procedure(const struct update_data *ud)
* Now we tried the usual fetch, but `oid` may
* not be reachable from any of the refs.
*/
- if (!is_tip_reachable(ud->sm_path, &ud->oid) &&
+ if (is_tip_reachable(ud->sm_path, &ud->oid) &&
fetch_in_submodule(ud->sm_path, ud->depth, ud->quiet, &ud->oid))
return die_message(_("Fetched in submodule path '%s', but it did not "
"contain %s. Direct fetching of that commit failed."),
I'm able to using the GIT_TRACE= of git submodule update arrive at the
correct fetching from origin in the test case where before the code fix
it was fetching from remote o1.
trace: run_command: cd sub; unset GIT_PREFIX; GIT_DIR=.git git rev-list -n 1 27fe1b65df6f55a58636afcba364dfcb64916cd6 --not --all
trace: start_command: /home/dan/repos/git/git rev-list -n 1 27fe1b65df6f55a58636afcba364dfcb64916cd6 --not --all
trace: built-in: git rev-list -n 1 27fe1b65df6f55a58636afcba364dfcb64916cd6 --not --all
trace: run_command: cd sub; unset GIT_PREFIX; GIT_DIR=.git git rev-list -n 1 27fe1b65df6f55a58636afcba364dfcb64916cd6 --not --all
trace: start_command: /home/dan/repos/git/git rev-list -n 1 27fe1b65df6f55a58636afcba364dfcb64916cd6 --not --all
trace: built-in: git rev-list -n 1 27fe1b65df6f55a58636afcba364dfcb64916cd6 --not --all
trace: run_command: cd sub; unset GIT_PREFIX; GIT_DIR=.git git fetch origin 27fe1b65df6f55a58636afcba364dfcb64916cd6
trace: start_command: /home/dan/repos/git/git fetch origin 27fe1b65df6f55a58636afcba364dfcb64916cd6
As Sergei said in the original referenced message "a submodule where the commit cannot be fetched by simply
`git fetch` and needs a direct fetch".
So this is the test case that I'm having trouble generating.
