analysis; workaround

doc/bugs/backend_version_upgrade_leaves_repo_unusable.mdwn

@@ -1,6 +1,10 @@
 foo is a local repo, bar is a bare remote.
 
-I upgraded foo's git-annex to 0.20110325 and upgraded a local repo backend to version 2. I then ran `git annex copy . --to bar` and checked the remote. This created WORM:SHA512--123123 files in annex/objects. Understandable but unwanted. So I upgraded git-annex on bar's machine, as well.
+I upgraded foo's git-annex to 0.20110325 and upgraded a local repo backend
+to version 2. I then ran `git annex copy . --to bar` and checked the
+remote. This created WORM:SHA512--123123 files in annex/objects.
+Understandable but unwanted. So I upgraded git-annex on bar's machine, as
+well.
 
     % git annex copy . --to bar
     copy quux (checking bar) git-annex-shell: Repository version 1 is not supported. Upgrade this repository: git-annex upgrade (to bar)
@@ -33,3 +37,23 @@ Running the copy job again, I am still getting the same error as above (as expec
 > joey@kitenet.net if you don't want to post them here. --[[Joey]]
 
 >> Sent. -- RichiH
+
+>>> Ok, I'm going to go work on my reading comprehension. I see now
+>>> that you
+>>> explained the problem pretty well. The problem is caused by these
+>>> few weird v1 mixed with v2 keys in the annex.
+>>> Ones like "annex/objects/WORM:SHA512--$sha512".
+>>>
+>>> That's a v1 key, but a corrupt form of the key; it's missing the 
+>>> size and mtime fields that all WORM keys have in v1. And 
+>>> the filename is itself a key, a v2 SHA512 key. My guess at what
+>>> happened is that these were created when you did the `git annex copy`
+>>> to the v1 bare repo.
+>>>
+>>> So, assuming none of these are the only copy of your data
+>>> (which you should check), the best thing to do is delete those
+>>> keys, and re-run the copy now that it's upgraded. Not sure 
+>>> it even makes sense to fix the crash. I should probably focus
+>>> on fixing what let these mixed keys be created by the mixed-version
+>>> copy.
+>>> --[[Joey]]