[MERGE] Improve tests for the behaviour of Tree.iter_changes for missing paths that are only present in one tree, and fix found bugs. (Robert Collins)

[Stephen J. Turnbull]

Robert Collins writes:

 > That would make it less objectionable for me. But still - this is not an
 > *exceptional* circumstance; using exceptions for situation-normal flow
 > control is pretty ugly IMO.

I suppose you've complained to the BDFL, then?<wink>  I'm referring to
GeneratorExit and StopIteration, of course.