test-bot: Fix emtpy --tap argument
test-bot: Fix emtpy --tap argument

Closes Linuxbrew/brew#82.

Signed-off-by: Shaun Jackman <b580dab3251a9622aba3803114310c23fdb42900@gmail.com>

Linuxbrew/brew,hanxue/linuxbrew,rwhogg/brew,rwhogg/brew,Linuxbrew/brew,maxim-belkin/brew,Linuxbrew/brew,hanxue/linuxbrew,hanxue/linuxbrew,maxim-belkin/brew,rwhogg/brew,maxim-belkin/brew,Linuxbrew/brew