Compactor case clause error

[nickva]

Noticed a shard that could not be compacted. The compaction would start then would crash.

{function_clause,[
    {couch_bt_engine_compactor,'-copy_docs/4-inlined-2-',[
       {3,<<138,72,.....>>},
       [],
       leaf,
       {0,0,[]}
      ], [{file,"src/couch_bt_engine_compactor.erl"},{line,407}]
    },
    {couch_key_tree,mapfold_simple,4,[{file,"src/couch_key_tree.erl"},{line,465}]},
    {couch_key_tree,mapfold_simple,4,[{file,"src/couch_key_tree.erl"},{line,474}]},
    {couch_key_tree,mapfold,3,[{file,"src/couch_key_tree.erl"},{line,458}]},
    {couch_bt_engine_compactor,'-copy_docs/4-fun-5-',3,[{file,"src/couch_bt_engine_compactor.erl"},{line,406}]},
    {lists,map_1,2,[{file,"lists.erl"},{line,1320}]},
    {lists,map_1,2,[{file,"lists.erl"},{line,1320}]},
    {lists,map,2,[{file,"lists.erl"},{line,1315}]}
]}

That seems to come from:

couchdb/src/couch/src/couch_bt_engine_compactor.erl

Line 408 in a326cdc

({RevPos, RevId}, #leaf{ptr = Sp} = Leaf, leaf, SizesAcc) ->

where we get [] instead of #leaf{ptr = Sp} = Leaf.

The only fix so far is to delete the copy and let the other nodes re-replicate the data.