The previous version used fmt.Fscanln which sounds like it should scan
for a whole line, but it actually errors if there is more than a single
word/token given. You can see this here https://play.golang.org/p/1RYXdtPSbk
And looking at the only usage of this function in core it won't break
anything to change it to actually return whole lines instead.
line, err := ui.Ask("[c] Clean up and exit, [a] abort without cleanup, or [r] retry step (build may fail even if retry succeeds)?")
Closes#4474
242ed49ecb