Upgrade munin-node to be able to handle dirtyconfig capability
|Reported by:||snide||Owned by:||janl|
In #836, munin-master gained the capability of dirtyconfig.
Since the part of the protocol isn't implemented in the node, the plugins don't have a way to know if the master expects fetch with the config or not.
The node should set the environment variable MUNIN_CAP_DIRTYCONFIG before executing plugins to avoid for the plugin to send the values 2 times if not needed.