Allow easy de-activation of `fabric`'s `env.parallel` via a shell variable.
Allow easy de-activation of `fabric`'s `env.parallel` via a shell variable.

1flow/1flow,WillianPaiva/1flow,WillianPaiva/1flow,WillianPaiva/1flow,1flow/1flow,WillianPaiva/1flow,1flow/1flow,1flow/1flow,1flow/1flow,WillianPaiva/1flow