Merge branch 'nd/war-on-nul-in-commit'

* nd/war-on-nul-in-commit:
  commit_tree(): refuse commit messages that contain NULs
  Convert commit_tree() to take strbuf as message
  merge: abort if fails to commit

Conflicts:
	builtin/commit.c
	commit.c
	commit.h

builtin/commit-tree.c

@@ -98,7 +98,7 @@ int cmd_commit_tree(int argc, const char **argv, const char *prefix)
 			die_errno("git commit-tree: failed to read");
 	}
 
-	if (commit_tree(buffer.buf, tree_sha1, parents, commit_sha1, NULL)) {
+	if (commit_tree(&buffer, tree_sha1, parents, commit_sha1, NULL)) {
 		strbuf_release(&buffer);
 		return 1;
 	}