sequencer: warn when internal merge may be suboptimal due to renameLimit

When many files were renamed, the recursive merge strategy stopped
detecting renames and left many paths with delete/modify conflicts,
without any warning about what was going on or providing any hints about
how to tell Git to spend more cycles to detect renames.

Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: newren

sequencer.c

@@ -462,6 +462,7 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
 	if (is_rebase_i(opts) && clean <= 0)
 		fputs(o.obuf.buf, stdout);
 	strbuf_release(&o.obuf);
+	diff_warn_rename_limit("merge.renamelimit", o.needed_rename_limit, 0);
 	if (clean < 0)
 		return clean;