merge with /dev/null as base, instead of punting O==empty case

diff --git a/diff-tree.c b/diff-tree.c
index ed323d877cad1e78e08f84c1e9ee1ebb09f05d91..09d16ad6619d7e95959adf2003a8d0f8626491ce 100644 (file)
--- a/diff-tree.c
+++ b/diff-tree.c
@@ -3,6 +3,7 @@
 #include "commit.h"
 
 static int show_root_diff = 0;
+static int no_commit_id = 0;
 static int verbose_header = 0;
 static int ignore_merges = 1;
 static int read_stdin = 0;
@@ -29,7 +30,8 @@ static int call_diff_flush(void)
                return 0;
        }
        if (header) {
-               printf("%s%c", header, diff_options.line_termination);
+               if (!no_commit_id)
+                       printf("%s%c", header, diff_options.line_termination);
                header = NULL;
        }
        diff_flush(&diff_options);
@@ -231,6 +233,10 @@ int main(int argc, const char **argv)
                        show_root_diff = 1;
                        continue;
                }
+               if (!strcmp(arg, "--no-commit-id")) {
+                       no_commit_id = 1;
+                       continue;
+               }
                usage(diff_tree_usage);
        }
        if (diff_options.output_format == DIFF_FORMAT_PATCH)