Make task work on Linux based agents

[never-ok]

I'm getting the following error when trying to run task on Linux agent (Ubuntu 17.04):

2018-04-30T10:15:32.2770404Z ##[error]A supported task execution handler was not found. This error usually means the task does not carry an implementation that is compatible with your current operating system. Contact the task author for more details.
2018-04-30T10:15:32.2815678Z ##[section]Finishing: (re)Hydrate Build Variables https://rmdartifacts.blob.core.windows.net/buildartifacts/variables.json

[fredgate]

Exact same error.
It would be a great feature, especially that the docker image of the VSTS agent proposed by microsfot is based on a Linux.