range_set: fix coalescing bug when range is a subset of another
When coalescing ranges, sort_and_merge_range_set() unconditionally
assumes that the end of a range being folded into a preceding range
should become the end of the coalesced range. This assumption, however,
is invalid when one range is a subset of another. For example, given
ranges 1-5 and 2-3 added via range_set_append_unsafe(),
sort_and_merge_range_set() incorrectly coalesces them to range 1-3
rather than the correct union range 1-5. Fix this bug.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>