sudo for foreman

[pencilcheck]

rbenv/rbenv#127

As mentioned in the issue above, foreman with rbenv doesn't work since sudo changes the env, but there is a workaround, just change

sudo_cmd to sudo $(rbenv which foreman)
and remove the bundler exec foreman in the export command as appropriately however I don't know if this is the best solution.

[d4be4st]

moved to https://github.com/mina-deploy/mina-foreman