DAO error when updating a plugin

[subnetmarco]

I am encountering the following problem when trying to update a plugin:

2015/09/24 17:46:29 [error] 73861#0: *17 lua coroutine: runtime error: ./kong/dao/cassandra/base_dao.lua:423: attempt to index local 'old_t' (a nil value)
stack traceback:
coroutine 0:
    ./kong/dao/cassandra/base_dao.lua: in function 'fix_tables'
    ./kong/dao/cassandra/base_dao.lua:427: in function 'fix_tables'
    ./kong/dao/cassandra/base_dao.lua:454: in function 'update'
    ./kong/api/crud_helpers.lua:114: in function 'patch'
    ./kong/api/routes/apis.lua:87: in function <./kong/api/routes/apis.lua:86>
coroutine 1:
    [C]: in function 'resume'
    /usr/local/share/lua/5.1/lapis/application.lua:652: in function 'handler'
    /usr/local/share/lua/5.1/lapis/application.lua:393: in function 'resolve'
    /usr/local/share/lua/5.1/lapis/application.lua:402: in function </usr/local/share/lua/5.1/lapis/application.lua:400>
    [C]: in function 'xpcall'
    /usr/local/share/lua/5.1/lapis/application.lua:400: in function 'dispatch'
    /usr/local/share/lua/5.1/lapis/nginx.lua:181: in function 'serve'
    content_by_lua(nginx.conf:136):8: in function <content_by_lua(nginx.conf:136):1>, client: 127.0.0.1, server: , request: "PATCH /apis/hello.com/plugins/34f70cdb-e5bf-4e67-cea7-fbccada6d3ff HTTP/1.1", host: "127.0.0.1:8001"
2015/09/24 17:46:29 [error] 73861#0: *17 [lua] app.lua:113: handle_error(): /usr/local/share/lua/5.1/lapis/application.lua:655: ./kong/dao/cassandra/base_dao.lua:423: attempt to index local 'old_t' (a nil value)
stack traceback:
    ./kong/dao/cassandra/base_dao.lua: in function 'fix_tables'
    ./kong/dao/cassandra/base_dao.lua:427: in function 'fix_tables'
    ./kong/dao/cassandra/base_dao.lua:454: in function 'update'
    ./kong/api/crud_helpers.lua:114: in function 'patch'
    ./kong/api/routes/apis.lua:87: in function <./kong/api/routes/apis.lua:86>

stack traceback:
    [C]: in function 'error'
    /usr/local/share/lua/5.1/lapis/application.lua:655: in function 'handler'
    /usr/local/share/lua/5.1/lapis/application.lua:393: in function 'resolve'
    /usr/local/share/lua/5.1/lapis/application.lua:402: in function </usr/local/share/lua/5.1/lapis/application.lua:400>
    [C]: in function 'xpcall'
    /usr/local/share/lua/5.1/lapis/application.lua:400: in function 'dispatch'
    /usr/local/share/lua/5.1/lapis/nginx.lua:181: in function 'serve'
    content_by_lua(nginx.conf:136):8: in function <content_by_lua(nginx.conf:136):1>, client: 127.0.0.1, server: , request: "PATCH /apis/hello.com/plugins/34f70cdb-e5bf-4e67-cea7-fbccada6d3ff HTTP/1.1", host: "127.0.0.1:8001"

Steps to reproduce:

• Add an API

curl -d "request_host=hello.com&upstream_url=http://httpbin.org" 127.0.0.1:8001/apis

• Add an empty request transformation plugin

curl -d "name=request-transformer" 127.0.0.1:8001/apis/hello.com/plugins/

• Update the transformation plugin with a config

curl -X PATCH -d "name=request-transformer&config.add.headers=pippo:wot, host:marco.com" 127.0.0.1:8001/apis/hello.com/plugins/{plugin_id}