[morelisp]

> But it's not always so easy : you notice that you actually broke something down the line in the backend. You have to fix it (in your library), and do it all over again. You can also have libraries depending on other libraries, multiplying the effort when you messed up something.

Since this is Go, it's trivial to point in-development branches of downstream projects to an in-development branch of a dependency before merging it for those projects' testing processes. (This still doesn't cover 100% of cases of course, but nothing does. The better answer is not to over-factor in the first place.)