basho/riak_kv — pull request #373 by jonmeredith (2012-07-24 19:10:31+00:00)
Title: Changed semantics of backend:drop - backend must close all handles.

Resolves issues around eleveldb locking and handoff.

Should fix errors like this with 1.2.0rc2

```
2012-07-23 22:01:45.831 [error] <0.648.0>@riak_kv_vnode:delete:575 Failed to drop riak_kv_eleveldb_backend. Reason: {error_db_destroy,"IO error: lock ./data/leveldb/114179815416476790484662877555959610910619729920/LOCK: Resource temporarily unavailable"}
2012-07-24 00:01:24.486 [error] <0.1766.0>@riak_kv_vnode:init:265 Failed to start riak_kv_eleveldb_backend Reason: {db_open,"IO error: lock ./data/leveldb/3882113724160210876478537836902626
77096107081728/LOCK: Resource temporarily unavailable"}
```