Created attachment 626368 [details, diff] patch for qt5-build.class looks like a typo to me. Incidentally, it doesn't affect execution yet, but might if the script gets changed. Attached proposed patch.
Not a typo. The fallthrough is intentional.
I understand the failthrough, but why the line ends with ";&" and not simple ";" ?
Eh, nevermind. It seems like a new or at least obscure bash "feature"...