chunkbuffer: use for/else to detect end of iteration

changegroup*(): use enumerate when possible

changegroupsubset(): with the fix, prune() is actually useful in the testsuite

test-permissions: echo commands to make output readable

changegroupsubset: simplify knownheads/has_cl_set computation

changegroupsubset(): ancestors() is not inclusive, we need to remove the "heads"

changegroupsubset(): move comment at the right place

changegroupsubset(): refactor the prune() functions

Merge with stable

help: make helptable a list instead of a tuple The table should always have been a list so that extensions can append their own help topics -- hgsubversion would like to do this now.