bug: submodule update fails to fetch

[Sergei Golubchik <vuvova@gmail.com>]

Hi,

Sometimes (my local repository has lots of branches) after switching
branches

  git submodule update --init --recursive

fails with something like

  fatal: transport 'file' not allowed
  fatal: Fetched in submodule path 'wsrep-lib', but it did not contain e238c0d240c2557229b0523a4a032f3cf8b41639. Direct fetching of that commit failed.

the submodule transport is not 'file' (it's https) and the direct
fetching of the commit actually works:

  cd wsrep-lib
  git fetch origin e238c0d240c2557229b0523a4a032f3cf8b41639
  git checkout e238c0d240c2557229b0523a4a032f3cf8b41639
  cd ..

after that

  git submodule update --init --recursive

succeeds. This happens deterministically, but depends on the old and new
commits in the last checkout. As a workaround we've had to change our CI to do

  git submodule foreach --recursive 'git fetch origin $sha1;git checkout --force FETCH_HEAD'

This is the bit from `git bugreport`:

[System Info]
git version:
git version 2.39.3
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Linux 5.15.88-gentoo #1 SMP Wed Feb 15 16:42:45 CET 2023 x86_64
compiler info: gnuc: 11.3
libc info: glibc: 2.36
$SHELL (typically, interactive shell): /bin/bash

[Enabled Hooks]

Regards,
Sergei