lookup: check for dirstate damage on failure

keyword: rename matcher() to match() mimicking changes in main

tests: test for dispatch on [defaults]: more clearly differing output Using '-r null' instead of '-v' as the overriden command default. The latter did not have any effect on output, thus not giving much indication on whether the modified defaults were really in use or not.

merge: whitespace cleanup

revlog: add test for 7659eecd9da2 (issue1678)

changegroup: the node list might be an empty generator (fix issue1678)

store encoding: .i/.d encoding for non-store repo (broken by 810387f59696)

replace "i in range(len(xs))" with "i, x in enumerate(xs)" The remaining occurrences should be the ones where "xs" is mutated or where "i" is used for index arithmetic.