Fwd: Possible git bug in commit-graph: "invalid commit position"

From: Gary Oberbrunner <garyo@oberbrunner.com>
Date: Jan 20, 2020, 17:32 UTC
Message-ID: <CAFChFyi5J-mb+rshtF7U2m=MtPzEPUa+V1_qbEXC=-LdQ218yA@mail.gmail.com>
In-Reply-To: <CAFChFygiaMsUJC5Kfpnk26DLWbY0gPdNJpZ_gLMf4utZ6_oZxA@mail.gmail.com>

I'm running git 2.24.1 on Linux/WSL, and sometimes git fails with this error:
```
% git diff --cached
fatal: invalid commit position. commit-graph is likely corrupt
```
Usually that error goes away after I do a few more git operations, but
I haven't been able to discern a pattern yet. It's not always with
"diff", can be any git command as far as I can tell.
Perhaps it started after I enabled the commit-graph stuff:
```
[core]
        editor = emacsclient -c -a \"\"
        preloadindex = true
        fscache = true
        autocrlf = false
        commitGraph = true
        writeCommitGraph = true
```
In fact, when I turn off `commitGraph`, the error goes away. But as I
say, sometimes it goes away of its own accord.

Googling turns up almost nothing on this error. I have no idea if I've done something wrong to corrupt the commit graph, or if it's a git bug. If there's anything I can do to help debug it, I'd be happy to -- just let me know.

-- 
Gary