As noted in this thread yesterday, I see an odd behaviour of qmake:
SOURCE and HEADER variables (and possibly others, too) seem to remember the values of past executions of qmake.
So if I only use SOURCE += ... (as seen in many tutorials), I'll inevitably run into troubles because there's some leftover references in the variables.

1st question: Is this behaviour as it should be? Or would you see that as a bug?
2nd question: If bug, where do I report it?