Merge branch 'jk/simplify-csum-file-sha1fd-check'

Code simplification.

* jk/simplify-csum-file-sha1fd-check:
  sha1fd_check: die when we cannot open the file

csum-file.c

@@ -130,14 +130,10 @@ struct sha1file *sha1fd_check(const char *name)
 
 	sink = open("/dev/null", O_WRONLY);
 	if (sink < 0)
-		return NULL;
+		die_errno("unable to open /dev/null");
 	check = open(name, O_RDONLY);
-	if (check < 0) {
-		int saved_errno = errno;
-		close(sink);
-		errno = saved_errno;
-		return NULL;
-	}
+	if (check < 0)
+		die_errno("unable to open '%s'", name);
 	f = sha1fd(sink, name);
 	f->check_fd = check;
 	return f;