doc/bugs/old_data_isn__39__t_unused_after_migration.mdwn

@@ -0,0 +1,47 @@
+Old data isn't listed as unused after migrating backends:
+
+    #!/bin/bash
+    
+    BASE=/tmp/migrate-bug-2
+    set -x
+    chmod -R +w $BASE
+    rm -rf $BASE
+    mkdir -p $BASE
+    cd $BASE
+    
+    # create annex
+    git init .
+    git annex init
+    
+    # make a big (sparse) file and add it
+    dd if=/dev/zero of=bigfile bs=1 count=0 seek=1G
+    git annex add --backend WORM bigfile
+    git commit -m 'added bigfile'
+    
+    # migrate it
+    git annex migrate --backend SHA256 bigfile
+    
+    # status shows 2 keys taking up 2G
+    git annex status
+    
+    # but nothing is unused
+    git annex unused
+
+Output:
+
+    ++ git annex status
+    supported backends: SHA256 SHA1 SHA512 SHA224 SHA384 SHA256E SHA1E SHA512E SHA224E SHA384E WORM URL
+    supported remote types: git S3 bup directory rsync web hook
+    known repositories: 
+            ede95a82-1166-11e1-a475-475d55eb0f8f -- here
+    local annex keys: 2
+    local annex size: 2 gigabytes
+    visible annex keys: 1
+    visible annex size: 1 gigabyte
+    backend usage: 
+            WORM: 1
+            SHA256: 1
+    ++ git annex unused
+    unused . (checking for unused data...) (checking master...) ok
+
+The two files are hardlinked, so it's not taking up extra space, but it would be nice to be able to remove the old keys.