Set --stop-on-failure by default
Continuing on failure is largely pointless since you need to correct the failure anyway before what you told
kdesrc-build to do will actually work. You might as well correct it as soon as it happens.
Continuing anyway may save some time since there's a chance that some later modules will build successfully, but it's also confusing since there will be a large number of "downstream" failures and you will have to figure out which one is the first one that will allow others to start building. This seems like it should be considered experts-only behavior.