report on git repo getting broken

doc/bugs/annex_merge__breaks_git_repository__33__.mdwn

@@ -0,0 +1,55 @@
+### Please describe the problem.
+
+References of the struggle with more background:
+- [https://github.com/datalad/datalad/issues/7608](https://github.com/datalad/datalad/issues/7608)
+- [https://github.com/datalad/datalad/issues/7609](https://github.com/datalad/datalad/issues/7609)
+
+### What steps will reproduce the problem?
+
+```
+$> (set -e; cd /tmp/; rm -rf ds002144*; git clone http://github.com/OpenNeuroDatasets/ds002144 ; cd ds002144; git fsck; mkdir /tmp/ds002144-2; (cd /tmp/ds002144-2; git init; git annex init; ); git remote add --fetch datalad-public /tmp/ds002144-2; git fsck; git annex merge; git fsck; )
+
+```
+
+### What version of git-annex are you using? On what operating system?
+
+```
+10.20240430+git26-g5f61667f27-1~ndall+1%
+```
+
+### Please provide any additional information below.
+
+[[!format sh """
+
+$> (set -ex; cd /tmp/; rm -rf ds002144*; git clone http://github.com/OpenNeuroDatasets/ds002144 ; cd ds002144; git fsck; mkdir /tmp/ds002144-2; (cd /tmp/ds002144-2; git init; git annex init; ); git remote add --fetch datalad-public /tmp/ds002144-2; git fsck; git annex merge; git fsck; )
+...
++/bin/zsh:80> git fsck
+Checking object directories: 100% (256/256), done.
+Checking objects: 100% (4759/4759), done.
++/bin/zsh:80> git annex merge
+(merging datalad-public/git-annex into git-annex...)
+(recording state in git...)
+
+  Remote origin not usable by git-annex; setting annex-ignore
+
+  http://github.com/OpenNeuroDatasets/ds002144/config download failed: Not Found
+merge git-annex ok
++/bin/zsh:80> git fsck
+Checking object directories: 100% (256/256), done.
+Checking objects: 100% (4759/4759), done.
+broken link from    tree 4089998623737d39cd3f5d6fdfa89b164898e464
+              to    tree ae2937297eb1b4f6c9bfdfcf9d7a41b1adcea32e
+broken link from    tree 8ba58233cd121b97d5c918a6ba7c3a8c56fd38b1
+              to    tree b78b723042e6d7a967c806b52258e8554caa1696
+missing tree b78b723042e6d7a967c806b52258e8554caa1696
+missing tree ae2937297eb1b4f6c9bfdfcf9d7a41b1adcea32e
+
+"""]]
+
+### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
+
+there are good and there are some bad days ;)
+
+[[!meta author=yoh]]
+[[!tag projects/openneuro]]
+