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
  ...

builtin/rerere.c

@@ -103,8 +103,8 @@ int cmd_rerere(int argc, const char **argv, const char *prefix)
 			return 0;
 		for (i = 0; i < merge_rr.nr; i++) {
 			const char *path = merge_rr.items[i].string;
-			const char *name = (const char *)merge_rr.items[i].util;
-			diff_two(rerere_path(name, "preimage"), path, path, path);
+			const struct rerere_id *id = merge_rr.items[i].util;
+			diff_two(rerere_path(id, "preimage"), path, path, path);
 		}
 	} else
 		usage_with_options(rerere_usage, options);