Does Git have a race condition with itself?

Git is at 2.47.1 and this happened as part of a routine
git -C /usr/src pull -j `nproc` --no-edit --no-ff -p and
git -C /usr/src rebase stable/14 stable/14+local:

Already up to date.
error: cannot lock ref 'HEAD': Unable to create '/usr/src/.git/HEAD.lock': File exists.

Another git process seems to be running in this repository, e.g.
an editor opened by 'git commit'. Please make sure all processes
are terminated then try again. If it still fails, a git process
may have crashed in this repository earlier:
remove the file manually to continue.
error: could not switch to stable/14+local

Maybe I should add a sleep command between git pull and git rebase. Would five seconds be sufficient?