fix output of skipped items
use find_item()
fix items not cancelling after auto dependency failure
do not mess with lists we're iterating over
fix check for DummyItem und BundleItem
move dependency graphing into utils
update test for 715e6589
better error message and debug info for dependency problems
do not rm -rf needlessly
don't prematurely raise exception when daisy-chaining concurrency-blocked items is unnecessary