fdset: set all collected fds to CLOEXEC in fdset_new_fill()

src/test/test-fdset.c

@@ -11,8 +11,8 @@
 #include "tmpfile-util.h"
 
 TEST(fdset_new_fill) {
-        int fd = -EBADF;
         _cleanup_fdset_free_ FDSet *fdset = NULL;
+        int fd = -EBADF, flags;
 
         log_close();
         log_set_open_when_needed(true);
@@ -50,6 +50,9 @@ TEST(fdset_new_fill) {
 
         assert_se(fdset_new_fill(/* filter_cloexec= */ 0, &fdset) >= 0);
         assert_se(fdset_contains(fdset, fd));
+        flags = fcntl(fd, F_GETFD);
+        assert_se(flags >= 0);
+        assert_se(FLAGS_SET(flags, FD_CLOEXEC));
         fdset = fdset_free(fdset);
         assert_se(fcntl(fd, F_GETFD) < 0);
         assert_se(errno == EBADF);