tests: improve "neomake#CancelJob with invalid job" (#898)
tests: improve "neomake#CancelJob with invalid job" (#898)

Ref: https://github.com/neomake/neomake/issues/897.
neomake/neomake,bonds/neomake,euclio/neomake,codeinabox/neomake,nerdrew/neomake,bonds/neomake,nerdrew/neomake,datanoise/neomake,neomake/neomake,euclio/neomake