Issue #20311: select.epoll.poll() now rounds the timeout away from zero,
instead of rounding towards zero. For example, a timeout of one microsecond is
now rounded to one millisecond, instead of being rounded to zero.
diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index c492224..ab2016a 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -1379,7 +1379,9 @@
         return NULL;
     }
     else {
-        timeout = (int)(dtimeout * 1000.0);
+        /* epoll_wait() has a resolution of 1 millisecond, round away from zero
+           to wait *at least* dtimeout seconds. */
+        timeout = (int)ceil(dtimeout * 1000.0);
     }
 
     if (maxevents == -1) {