diff-merges: introduce revs->first_parent_merges flag

This new field allows us to separate format of diff for merges from
'first_parent_only' flag which primary purpose is limiting history
traversal.

This change further localizes diff format selection logic into the
diff-merges.c file.

Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/revision.h b/revision.h
index f6bf860d19..ba2aef7921 100644
--- a/revision.h
+++ b/revision.h
@@ -194,6 +194,7 @@ struct rev_info {
 			combine_merges:1,
 			combined_all_paths:1,
 			dense_combined_merges:1,
+			first_parent_merges:1,
 			always_show_header:1;
 	int             ignore_merges:2;