Merge branch 'jc/rerere'

Code clean-up and minor fixes. * jc/rerere: (21 commits) rerere: un-nest merge() further rerere: use "struct rerere_id" instead of "char *" for conflict ID rerere: call conflict-ids IDs rerere: further clarify do_rerere_one_path() rerere: further de-dent do_plain_rerere() rerere: refactor "replay" part of do_plain_rerere() rerere: explain the remainder rerere: explain "rerere forget" codepath rerere: explain the primary codepath rerere: explain MERGE_RR management helpers rerere: fix benign off-by-one non-bug and clarify code rerere: explain the rerere I/O abstraction rerere: do not leak mmfile[] for a path with multiple stage #1 entries rerere: stop looping unnecessarily rerere: drop want_sp parameter from is_cmarker() rerere: report autoupdated paths only after actually updating them rerere: write out each record of MERGE_RR in one go rerere: lift PATH_MAX limitation rerere: plug conflict ID leaks rerere: handle conflicts with multiple stage #1 entries ...