Graphviz doesn't work anymore

[pauleil]

Redmine 1.2.1
Performed the patch, as specified in the instructions.

Adding

{{graphviz(
digraph G {
a ->b;
}
)}}


results in

Error executing the graphviz macro (undefined method `pop' for "\ndigraph G {\na ->b;\n}\n":String)

[pauleil]

Could you please update it? This is such a useful plugin. Thanks!