Re: Unable to de-init stubborn submodule

> What if we wanted to drop sha1collisiondetection/ as a submodule and
> replace it with a copy of what's now in sha1dc/? I ran into this with
> another project, but here's a way to reproduce it on git.git:
> 
>     (
>         rm -rf /tmp/git &&
>         git clone git@github.com:git/git.git /tmp/git
>         cd /tmp/git &&
>         git tag nuke-before &&
>         git submodule update --init &&
>         git rm -r .gitmodules sha1collisiondetection &&
>         git commit -m"Nuke sha1dc submodule" &&
>         cp -Rvp sha1dc sha1collisiondetection &&
>         git add sha1collisiondetection &&
>         git commit -m"Now it's not a submodule" &&
>         git tag nuke-after &&
>         git reset --hard nuke-before &&
>         git submodule update --init && # skip this and the below won't fail
>         git reset --hard nuke-after && # Emulate someone doing a pull
>         git ls-tree HEAD | grep sha1collisiondetection && # OK, shows "tree" not "commit"
>         test $(git rev-parse HEAD) == $(git -C sha1collisiondetection/ log -1 --pretty=format:%H) && echo OK || echo WTF
>     )
> 
> This results in a really bizarre state where according to ls-tree
> sha1collisiondetection is a tree at the current commit:
> 
>     040000 tree 81583289d96bdde4b366c243ab524ea28d895ea5    sha1collisiondetection
> 
> But git still believes there's a submodule there for some reason, and
> shows the log for the upstream sha1collisiondetection project:
> 
>     git -C sha1collisiondetection/ log -1
>     commit 19d97bf (HEAD, origin/master, origin/HEAD, master)
>     Merge: 3f14d1b c93f0b4
>     Author: Dan Shumow <shumow@gmail.com>
>     Date:   Sat Jul 1 12:36:15 2017 -0700
> 
>         Merge pull request #37 from avar/fixup-pull-request-34
> 
>         Fix endian detection logic for Sparc, little endian BSD etc.
> 
> Doing:
> 
>     git submodule deinit sha1collisiondetection
> 
> Does nothing to help, then I thought it might be:
> 
>     git config -f .git/config -l|grep ^submodule
>     submodule.sha1collisiondetection.active=true
>     submodule.sha1collisiondetection.url=https://github.com/cr-marcstevens/sha1collisiondetection.git
> 
> But running:
> 
>     git config --remove-section submodule.sha1collisiondetection
> 
> Doesn't help either, neither does removing the index:
> 
>     rm .git/index &&
>     git reset --hard
> 
> If you then do:
> 
>     rm -rf .git/modules
> 
> You'll get this error:
> 
>     git -C sha1collisiondetection/ log -1
>     fatal: Not a git repository: /tmp/git/sha1collisiondetection/../.git/modules/sha1collisiondetection
> 
> But I can't see what's still referencing it.
> 
> This problem is avoided if, as noted with a comment I skip:
> 
>     git submodule update --init
> 
> But I shouldn't need to remember to de-init a submodule before moving to
> a new commit that doesn't have it, least I end up in some seemingly
> unrecoverable state.
> 
> Am I missing something obvious here?